arch|cpu/x86: Add Kconfig option for x86 reset vector

Prepare for an implementation supporting the reset vector in RAM and
not the traditional 0xfffffff0.  Add a Kconfig symbol that can be used
in place of hardcoded values.

Change-Id: I6a814f7179ee4251aeeccb2555221616e944e03d
Signed-off-by: Marshall Dawson <marshalldawson3rd@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37485
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

6 files changed, 19 insertions, 11 deletions

diff --git a/src/arch/x86/Kconfig b/src/arch/x86/Kconfig
index 0e6f486d03..e27aec2463 100644
--- a/src/arch/x86/Kconfig
+++ b/src/arch/x86/Kconfig
@@ -87,6 +87,16 @@ config AP_IN_SIPI_WAIT
 	default n
 	depends on ARCH_X86 && SMP
 
+config X86_RESET_VECTOR
+	hex
+	depends on ARCH_X86
+	default 0xfffffff0
+	help
+	  Specify the location of the x86 reset vector.  In traditional devices
+	  this must match the architectural reset vector to produce a bootable
+	  image.  Nontraditional designs may use this to position the reset
+	  vector into its desired location.
+
 config RESET_VECTOR_IN_RAM
 	bool
 	depends on ARCH_X86
diff --git a/src/arch/x86/failover.ld b/src/arch/x86/failover.ld
index 334145a742..139136540c 100644
--- a/src/arch/x86/failover.ld
+++ b/src/arch/x86/failover.ld
@@ -14,7 +14,7 @@
 ENTRY(_start)
 
 MEMORY {
-	rom : ORIGIN = 0xffff0000, LENGTH = 64K
+	rom : ORIGIN = CONFIG_X86_RESET_VECTOR - 0xfff0, LENGTH = 64K
 }
 
 TARGET(binary)
diff --git a/src/arch/x86/id.ld b/src/arch/x86/id.ld
index 2a50f9ca4f..3d9ef37ab9 100644
--- a/src/arch/x86/id.ld
+++ b/src/arch/x86/id.ld
@@ -12,7 +12,7 @@
  */
 
 SECTIONS {
-	. = (0xffffffff - CONFIG_ID_SECTION_OFFSET) - (__id_end - __id_start) + 1;
+	. = (CONFIG_X86_RESET_VECTOR - CONFIG_ID_SECTION_OFFSET) - (__id_end - __id_start) + 0x10;
 	.id (.): {
 		KEEP(*(.id))
 	}
diff --git a/src/arch/x86/memlayout.ld b/src/arch/x86/memlayout.ld
index f8ae9f3918..b14fd624a7 100644
--- a/src/arch/x86/memlayout.ld
+++ b/src/arch/x86/memlayout.ld
@@ -50,7 +50,7 @@ SECTIONS
 	#include EARLY_MEMLAYOUT
 #elif ENV_BOOTBLOCK
 	/* arch/x86/bootblock.ld contains the logic for the ROMCC_BOOTBLOCK linking. */
-	BOOTBLOCK(0xffffffff - CONFIG_C_ENV_BOOTBLOCK_SIZE + 1,
+	BOOTBLOCK(CONFIG_X86_RESET_VECTOR - CONFIG_C_ENV_BOOTBLOCK_SIZE + 0x10,
 			CONFIG_C_ENV_BOOTBLOCK_SIZE)
 
 	#include EARLY_MEMLAYOUT
diff --git a/src/cpu/intel/fit/fit.ld b/src/cpu/intel/fit/fit.ld
index 6e30ea168a..2e65186e40 100644
--- a/src/cpu/intel/fit/fit.ld
+++ b/src/cpu/intel/fit/fit.ld
@@ -12,7 +12,7 @@
  */
 
 SECTIONS {
-	. = 0xffffffc0;
+	. = CONFIG_X86_RESET_VECTOR - 0x30; /* 0xffffffc0 */
 	.fit_pointer (.): {
 		KEEP(*(.fit_pointer))
 	}
diff --git a/src/cpu/x86/16bit/reset16.ld b/src/cpu/x86/16bit/reset16.ld
index c57cc96cdd..ec01810e73 100644
--- a/src/cpu/x86/16bit/reset16.ld
+++ b/src/cpu/x86/16bit/reset16.ld
@@ -11,16 +11,14 @@
  * GNU General Public License for more details.
  */
 
-/*
- *      _ROMTOP                 : The top of the ROM used where we
- *				  need to put the reset vector.
- */
+/* _RESET_VECTOR: typically the top of the ROM */
 
 SECTIONS {
 	/* Trigger an error if I have an unuseable start address */
-	_bogus = ASSERT(_start16bit >= 0xffff0000, "_start16bit too low. Please report.");
-	_ROMTOP = 0xfffffff0;
-	. = _ROMTOP;
+	_TOO_LOW = CONFIG_X86_RESET_VECTOR - 0xfff0;
+	_bogus = ASSERT(_start16bit >= _TOO_LOW, "_start16bit too low. Please report.");
+
+	. = CONFIG_X86_RESET_VECTOR;
 	.reset . : {
 		*(.reset);
 		. = 15;