acpi: Bump FADT to revision 6

Some of the revision 4 FADT fields were already updated to ACPI
spec revision 6, but not all of them. In addition the advertised
FADT revision was 3.

Implement all fields as defined in version 6 and bump the advertised
FADT revision to 6.

Also set all used access_size fields and x_gpe0_blk to sane values
as Windows 10 verifies those fields starting with FADT revision 5.

Fixes: https://ticket.coreboot.org/issues/109

Tested on Windows 10.

Change-Id: Ic649040025cd09ed3e490a521439ca4e681afbbf
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/39805
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Matt DeVillier <matt.devillier@gmail.com>

21 files changed, 138 insertions, 102 deletions

diff --git a/src/arch/x86/acpi.c b/src/arch/x86/acpi.c
index 6eded1d97a..a5c5c49473 100644
--- a/src/arch/x86/acpi.c
+++ b/src/arch/x86/acpi.c
@@ -1554,7 +1554,7 @@ int get_acpi_table_revision(enum acpi_tables table)
 {
 	switch (table) {
 	case FADT:
-		return ACPI_FADT_REV_ACPI_3_0;
+		return ACPI_FADT_REV_ACPI_6_0;
 	case MADT: /* ACPI 3.0: 2, ACPI 4.0/5.0: 3, ACPI 6.2b/6.3: 5 */
 		return 2;
 	case MCFG:
diff --git a/src/arch/x86/include/arch/acpi.h b/src/arch/x86/include/arch/acpi.h
index 644f52f2ce..f5ec9f1685 100644
--- a/src/arch/x86/include/arch/acpi.h
+++ b/src/arch/x86/include/arch/acpi.h
@@ -546,8 +546,8 @@ typedef struct acpi_fadt {
 	u32 flags;
 	acpi_addr_t reset_reg;
 	u8 reset_value;
-	u16 ARM_boot_arch;
-	u8 FADT_MinorVersion;
+	u16 ARM_boot_arch;	/* Revision 6 only, Revision 5: Must be zero */
+	u8 FADT_MinorVersion;	/* Revision 6 only, Revision 5: Must be zero */
 	u32 x_firmware_ctl_l;
 	u32 x_firmware_ctl_h;
 	u32 x_dsdt_l;
@@ -560,6 +560,11 @@ typedef struct acpi_fadt {
 	acpi_addr_t x_pm_tmr_blk;
 	acpi_addr_t x_gpe0_blk;
 	acpi_addr_t x_gpe1_blk;
+	/* Revision 5 */
+	acpi_addr_t sleep_control_reg;
+	acpi_addr_t sleep_status_reg;
+	/* Revision 6 */
+	u64 hypervisor_vendor_identity;
 } __packed acpi_fadt_t;
 
 /* FADT TABLE Revision values */
diff --git a/src/mainboard/emulation/qemu-q35/acpi_tables.c b/src/mainboard/emulation/qemu-q35/acpi_tables.c
index 29dcedf541..359c562e53 100644
--- a/src/mainboard/emulation/qemu-q35/acpi_tables.c
+++ b/src/mainboard/emulation/qemu-q35/acpi_tables.c
@@ -85,7 +85,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->reset_reg.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 0x06;
@@ -99,7 +99,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = 32;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -114,7 +114,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.bit_width = 16; /* Upper word is reserved and
 						Linux complains about 32 bit. */
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + 0x4;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -128,14 +128,14 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + 0x50;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = 32;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + 0x8;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
diff --git a/src/mainboard/lenovo/t400/fadt.c b/src/mainboard/lenovo/t400/fadt.c
index 3aeb8bc5c0..840dcd0a42 100644
--- a/src/mainboard/lenovo/t400/fadt.c
+++ b/src/mainboard/lenovo/t400/fadt.c
@@ -68,7 +68,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->reset_reg.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 0x06;
@@ -82,7 +82,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = 32;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -97,7 +97,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.bit_width = 16; /* Upper word is reserved and
 						Linux complains about 32 bit. */
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + 0x4;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -111,21 +111,21 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + 0x50;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = 32;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + 0x8;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = 128;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = pmbase + 0x20;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
diff --git a/src/mainboard/lenovo/x200/fadt.c b/src/mainboard/lenovo/x200/fadt.c
index 3aeb8bc5c0..840dcd0a42 100644
--- a/src/mainboard/lenovo/x200/fadt.c
+++ b/src/mainboard/lenovo/x200/fadt.c
@@ -68,7 +68,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->reset_reg.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 0x06;
@@ -82,7 +82,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = 32;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -97,7 +97,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.bit_width = 16; /* Upper word is reserved and
 						Linux complains about 32 bit. */
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + 0x4;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -111,21 +111,21 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + 0x50;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = 32;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + 0x8;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = 128;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = pmbase + 0x20;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
diff --git a/src/mainboard/roda/rk9/fadt.c b/src/mainboard/roda/rk9/fadt.c
index 3aeb8bc5c0..edcb3539b1 100644
--- a/src/mainboard/roda/rk9/fadt.c
+++ b/src/mainboard/roda/rk9/fadt.c
@@ -82,7 +82,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = 32;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -97,7 +97,7 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.bit_width = 16; /* Upper word is reserved and
 						Linux complains about 32 bit. */
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + 0x4;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -111,21 +111,21 @@ void acpi_create_fadt(acpi_fadt_t * fadt, acpi_facs_t * facs, void *dsdt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + 0x50;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = 32;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + 0x8;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = 128;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = pmbase + 0x20;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
diff --git a/src/soc/amd/picasso/acpi.c b/src/soc/amd/picasso/acpi.c
index 910d3e927e..c9a1179d52 100644
--- a/src/soc/amd/picasso/acpi.c
+++ b/src/soc/amd/picasso/acpi.c
@@ -171,7 +171,7 @@ void acpi_create_fadt(acpi_fadt_t *fadt, acpi_facs_t *facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_pm1a_cnt_blk.bit_width = 16;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = ACPI_PM1_CNT_BLK;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
diff --git a/src/soc/amd/stoneyridge/acpi.c b/src/soc/amd/stoneyridge/acpi.c
index 6a373fbd49..113d1e6b57 100644
--- a/src/soc/amd/stoneyridge/acpi.c
+++ b/src/soc/amd/stoneyridge/acpi.c
@@ -173,7 +173,7 @@ void acpi_create_fadt(acpi_fadt_t *fadt, acpi_facs_t *facs, void *dsdt)
 	fadt->x_pm1a_cnt_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_pm1a_cnt_blk.bit_width = 16;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = ACPI_PM1_CNT_BLK;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/apollolake/acpi.c b/src/soc/intel/apollolake/acpi.c
index 82ef3f1d38..fbfe33ff73 100644
--- a/src/soc/intel/apollolake/acpi.c
+++ b/src/soc/intel/apollolake/acpi.c
@@ -167,7 +167,7 @@ void soc_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.addrl = ACPI_BASE_ADDRESS + PM1_TMR;
-
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 
 	if (cfg->lpss_s0ix_enable)
 		fadt->flags |= ACPI_FADT_LOW_PWR_IDLE_S0;
diff --git a/src/soc/intel/baytrail/acpi.c b/src/soc/intel/baytrail/acpi.c
index ac0e29268b..3074f1a08f 100644
--- a/src/soc/intel/baytrail/acpi.c
+++ b/src/soc/intel/baytrail/acpi.c
@@ -171,7 +171,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 6;
@@ -179,7 +179,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -193,7 +193,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -207,21 +207,27 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = fadt->pm2_cnt_len * 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + PM2A_CNT_BLK;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
+	/*
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
+	 */
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = pmbase + GPE0_STS;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/braswell/acpi.c b/src/soc/intel/braswell/acpi.c
index b4e4746437..1e6cea298b 100644
--- a/src/soc/intel/braswell/acpi.c
+++ b/src/soc/intel/braswell/acpi.c
@@ -175,7 +175,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 6;
@@ -183,7 +183,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -197,7 +197,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -211,21 +211,27 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = fadt->pm2_cnt_len * 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + PM2A_CNT_BLK;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
+	/*
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
+	 */
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = pmbase + GPE0_STS;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/broadwell/acpi.c b/src/soc/intel/broadwell/acpi.c
index b93518954f..c45bd76731 100644
--- a/src/soc/intel/broadwell/acpi.c
+++ b/src/soc/intel/broadwell/acpi.c
@@ -226,7 +226,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 6;
@@ -234,7 +234,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -248,7 +248,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -262,24 +262,31 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = fadt->pm2_cnt_len * 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + PM2_CNT;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
-	fadt->x_gpe0_blk.space_id = 0;
-	fadt->x_gpe0_blk.bit_width = 0;
+	/*
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
+	 */
+	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
+	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
-	fadt->x_gpe0_blk.addrl = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
 	fadt->x_gpe0_blk.addrh = 0;
 
+
 	fadt->x_gpe1_blk.space_id = 1;
 	fadt->x_gpe1_blk.bit_width = 0;
 	fadt->x_gpe1_blk.bit_offset = 0;
diff --git a/src/soc/intel/cannonlake/acpi.c b/src/soc/intel/cannonlake/acpi.c
index 0c806b5d60..306fa1cbee 100644
--- a/src/soc/intel/cannonlake/acpi.c
+++ b/src/soc/intel/cannonlake/acpi.c
@@ -170,7 +170,7 @@ void soc_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/common/block/acpi/acpi.c b/src/soc/intel/common/block/acpi/acpi.c
index b848db446f..fe127a27e7 100644
--- a/src/soc/intel/common/block/acpi/acpi.c
+++ b/src/soc/intel/common/block/acpi/acpi.c
@@ -110,7 +110,6 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 {
 	const uint16_t pmbase = ACPI_BASE_ADDRESS;
 
-	/* Use ACPI 3.0 revision. */
 	fadt->header.revision = get_acpi_table_revision(FADT);
 
 	fadt->sci_int = acpi_sci_irq();
@@ -146,20 +145,37 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.addrl = RST_CNT;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_value = RST_CPU | SYS_RST;
 
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+
 
 	fadt->x_pm1b_evt_blk.space_id = 1;
 
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 
 	fadt->x_pm1b_cnt_blk.space_id = 1;
 
+	/*
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
+	 */
+	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
+	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
+	fadt->x_gpe0_blk.bit_offset = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
+	fadt->x_gpe0_blk.addrh = 0;
+
 	fadt->x_gpe1_blk.space_id = 1;
 
 	soc_fill_fadt(fadt);
diff --git a/src/soc/intel/icelake/acpi.c b/src/soc/intel/icelake/acpi.c
index 327dd112b8..ca74ab3b08 100644
--- a/src/soc/intel/icelake/acpi.c
+++ b/src/soc/intel/icelake/acpi.c
@@ -166,7 +166,7 @@ void soc_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/quark/acpi.c b/src/soc/intel/quark/acpi.c
index ca4d2d6f65..624eb7669e 100644
--- a/src/soc/intel/quark/acpi.c
+++ b/src/soc/intel/quark/acpi.c
@@ -35,7 +35,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + R_QNC_PM1BLK_PM1S;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -46,7 +46,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = fadt->pm1a_cnt_blk;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -57,7 +57,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = fadt->pm_tmr_blk;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
@@ -79,7 +79,7 @@ void acpi_fill_in_fadt(acpi_fadt_t *fadt)
 	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
 	fadt->x_gpe0_blk.addrh = 0;
 
diff --git a/src/soc/intel/skylake/acpi.c b/src/soc/intel/skylake/acpi.c
index dee44b6253..75f6b691ac 100644
--- a/src/soc/intel/skylake/acpi.c
+++ b/src/soc/intel/skylake/acpi.c
@@ -223,7 +223,6 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	const uint16_t pmbase = ACPI_BASE_ADDRESS;
 	config_t *config = config_of_soc();
 
-	/* Use ACPI 3.0 revision */
 	fadt->header.revision = get_acpi_table_revision(FADT);
 
 	fadt->sci_int = acpi_sci_irq();
@@ -275,7 +274,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 6;
@@ -283,7 +282,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -297,7 +296,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -311,22 +310,28 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = fadt->pm2_cnt_len * 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + PM2_CNT;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
-	fadt->x_gpe0_blk.space_id = 0;
-	fadt->x_gpe0_blk.bit_width = 0;
+	/*
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
+	 */
+	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
+	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
-	fadt->x_gpe0_blk.addrl = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
 	fadt->x_gpe0_blk.addrh = 0;
 
 	fadt->x_gpe1_blk.space_id = 1;
diff --git a/src/soc/intel/tigerlake/acpi.c b/src/soc/intel/tigerlake/acpi.c
index 29a46195cd..9e7ff56752 100644
--- a/src/soc/intel/tigerlake/acpi.c
+++ b/src/soc/intel/tigerlake/acpi.c
@@ -167,7 +167,7 @@ void soc_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
diff --git a/src/soc/intel/xeon_sp/skx/acpi.c b/src/soc/intel/xeon_sp/skx/acpi.c
index 2abdf91eaf..e9edc9917d 100644
--- a/src/soc/intel/xeon_sp/skx/acpi.c
+++ b/src/soc/intel/xeon_sp/skx/acpi.c
@@ -355,7 +355,6 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 {
 	const uint16_t pmbase = ACPI_BASE_ADDRESS;
 
-	/* Use ACPI 3.0 revision */
 	fadt->header.revision = get_acpi_table_revision(FADT);
 
 	fadt->sci_int = acpi_sci_irq();
@@ -410,7 +409,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->reset_reg.space_id = 1;
 	fadt->reset_reg.bit_width = 8;
 	fadt->reset_reg.bit_offset = 0;
-	fadt->reset_reg.access_size = 0;
+	fadt->reset_reg.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->reset_reg.addrl = 0xcf9;
 	fadt->reset_reg.addrh = 0;
 	fadt->reset_value = 6;
@@ -418,7 +417,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = pmbase + PM1_STS;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
@@ -432,7 +431,7 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = pmbase + PM1_CNT;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
@@ -446,22 +445,22 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm2_cnt_blk.space_id = 1;
 	fadt->x_pm2_cnt_blk.bit_width = fadt->pm2_cnt_len * 8;
 	fadt->x_pm2_cnt_blk.bit_offset = 0;
-	fadt->x_pm2_cnt_blk.access_size = 0;
+	fadt->x_pm2_cnt_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_pm2_cnt_blk.addrl = pmbase + PM2_CNT;
 	fadt->x_pm2_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = pmbase + PM1_TMR;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
-	fadt->x_gpe0_blk.space_id = 0;
-	fadt->x_gpe0_blk.bit_width = 0;
+	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
+	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
-	fadt->x_gpe0_blk.addrl = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
 	fadt->x_gpe0_blk.addrh = 0;
 
 	fadt->x_gpe1_blk.space_id = 1;
diff --git a/src/southbridge/intel/i82371eb/fadt.c b/src/southbridge/intel/i82371eb/fadt.c
index b26628d075..db1071a041 100644
--- a/src/southbridge/intel/i82371eb/fadt.c
+++ b/src/southbridge/intel/i82371eb/fadt.c
@@ -157,28 +157,28 @@ void acpi_create_fadt(acpi_fadt_t *fadt, acpi_facs_t *facs, void *dsdt)
 	fadt->x_pm1a_evt_blk.space_id = 1;
 	fadt->x_pm1a_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1a_evt_blk.bit_offset = 0;
-	fadt->x_pm1a_evt_blk.access_size = 0;
+	fadt->x_pm1a_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1a_evt_blk.addrl = fadt->pm1a_evt_blk;
 	fadt->x_pm1a_evt_blk.addrh = 0x0;
 
 	fadt->x_pm1b_evt_blk.space_id = 1;
 	fadt->x_pm1b_evt_blk.bit_width = fadt->pm1_evt_len * 8;
 	fadt->x_pm1b_evt_blk.bit_offset = 0;
-	fadt->x_pm1b_evt_blk.access_size = 0;
+	fadt->x_pm1b_evt_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm1b_evt_blk.addrl = fadt->pm1b_evt_blk;
 	fadt->x_pm1b_evt_blk.addrh = 0x0;
 
 	fadt->x_pm1a_cnt_blk.space_id = 1;
 	fadt->x_pm1a_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1a_cnt_blk.bit_offset = 0;
-	fadt->x_pm1a_cnt_blk.access_size = 0;
+	fadt->x_pm1a_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1a_cnt_blk.addrl = fadt->pm1a_cnt_blk;
 	fadt->x_pm1a_cnt_blk.addrh = 0x0;
 
 	fadt->x_pm1b_cnt_blk.space_id = 1;
 	fadt->x_pm1b_cnt_blk.bit_width = fadt->pm1_cnt_len * 8;
 	fadt->x_pm1b_cnt_blk.bit_offset = 0;
-	fadt->x_pm1b_cnt_blk.access_size = 0;
+	fadt->x_pm1b_cnt_blk.access_size = ACPI_ACCESS_SIZE_WORD_ACCESS;
 	fadt->x_pm1b_cnt_blk.addrl = fadt->pm1b_cnt_blk;
 	fadt->x_pm1b_cnt_blk.addrh = 0x0;
 
@@ -192,21 +192,21 @@ void acpi_create_fadt(acpi_fadt_t *fadt, acpi_facs_t *facs, void *dsdt)
 	fadt->x_pm_tmr_blk.space_id = 1;
 	fadt->x_pm_tmr_blk.bit_width = fadt->pm_tmr_len * 8;
 	fadt->x_pm_tmr_blk.bit_offset = 0;
-	fadt->x_pm_tmr_blk.access_size = 0;
+	fadt->x_pm_tmr_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
 	fadt->x_pm_tmr_blk.addrl = fadt->pm_tmr_blk;
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
 	fadt->x_gpe0_blk.space_id = 1;
 	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
 	fadt->x_gpe0_blk.bit_offset = 0;
-	fadt->x_gpe0_blk.access_size = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
 	fadt->x_gpe0_blk.addrh = 0x0;
 
 	fadt->x_gpe1_blk.space_id = 1;
 	fadt->x_gpe1_blk.bit_width = fadt->gpe1_blk_len * 8;
 	fadt->x_gpe1_blk.bit_offset = 0;
-	fadt->x_gpe1_blk.access_size = 0;
+	fadt->x_gpe1_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
 	fadt->x_gpe1_blk.addrl = fadt->gpe1_blk;
 	fadt->x_gpe1_blk.addrh = 0x0;
 
diff --git a/src/southbridge/intel/lynxpoint/lpc.c b/src/southbridge/intel/lynxpoint/lpc.c
index 21da7d24d7..d9ef5cc538 100644
--- a/src/southbridge/intel/lynxpoint/lpc.c
+++ b/src/southbridge/intel/lynxpoint/lpc.c
@@ -852,25 +852,17 @@ void acpi_fill_fadt(acpi_fadt_t *fadt)
 	fadt->x_pm_tmr_blk.addrh = 0x0;
 
 	/*
-	 * We don't set `fadt->x_gpe0_blk` for Lynx Point LP since the correct
-	 * bit width is 128 * 2, which is too large for an 8 bit unsigned int.
-	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`.
+	 * Windows 10 requires x_gpe0_blk to be set starting with FADT revision 5.
+	 * The bit_width field intentionally overflows here.
+	 * The OSPM can instead use the values in `fadt->gpe0_blk{,_len}`, which
+	 * seems to work fine on Linux 5.0 and Windows 10.
 	 */
-	if (!pch_is_lp()) {
-		fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
-		fadt->x_gpe0_blk.bit_width = 2 * 64;
-		fadt->x_gpe0_blk.bit_offset = 0;
-		fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_BYTE_ACCESS;
-		fadt->x_gpe0_blk.addrl = pmbase + GPE0_STS;
-		fadt->x_gpe0_blk.addrh = 0x0;
-	} else {
-		fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
-		fadt->x_gpe0_blk.bit_width = 0;
-		fadt->x_gpe0_blk.bit_offset = 0;
-		fadt->x_gpe0_blk.access_size = 0;
-		fadt->x_gpe0_blk.addrl = 0x0;
-		fadt->x_gpe0_blk.addrh = 0x0;
-	}
+	fadt->x_gpe0_blk.space_id = ACPI_ADDRESS_SPACE_IO;
+	fadt->x_gpe0_blk.bit_width = fadt->gpe0_blk_len * 8;
+	fadt->x_gpe0_blk.bit_offset = 0;
+	fadt->x_gpe0_blk.access_size = ACPI_ACCESS_SIZE_DWORD_ACCESS;
+	fadt->x_gpe0_blk.addrl = fadt->gpe0_blk;
+	fadt->x_gpe0_blk.addrh = 0x0;
 
 	fadt->x_gpe1_blk.space_id = ACPI_ADDRESS_SPACE_IO;
 	fadt->x_gpe1_blk.bit_width = 0;