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authorPatrick Rudolph <siro@das-labor.org>2018-12-09 10:48:59 +0100
committerPatrick Rudolph <siro@das-labor.org>2020-08-19 09:06:43 +0000
commite563815e059ef5881a42e6f8b37094783771d5a7 (patch)
tree7641211d03c315d37176717cbf37588ec4ebd38b /Documentation/arch
parentad7b2e23ab5954f150a4b2f62378f1e7133e56c9 (diff)
downloadcoreboot-e563815e059ef5881a42e6f8b37094783771d5a7.tar.xz
arch/x86/boot: Jump to payload in protected mode
* On ARCH_RAMSTAGE_X86_64 jump to the payload in protected mode. * Add a helper function to jump to arbitrary code in protected mode, similar to the real mode call handler. * Doesn't affect existing x86_32 code. * Add a macro to cast pointer to uint32_t that dies if it would overflow on conversion Tested on QEMU Q35 using SeaBIOS as payload. Tested on Lenovo T410 with additional x86_64 patches. Change-Id: I6552ac30f1b6205e08e16d251328e01ce3fbfd14 Signed-off-by: Patrick Rudolph <siro@das-labor.org> Reviewed-on: https://review.coreboot.org/c/coreboot/+/30118 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Diffstat (limited to 'Documentation/arch')
-rw-r--r--Documentation/arch/x86/index.md4
1 files changed, 3 insertions, 1 deletions
diff --git a/Documentation/arch/x86/index.md b/Documentation/arch/x86/index.md
index 81eb51925a..7b9e1fcfa0 100644
--- a/Documentation/arch/x86/index.md
+++ b/Documentation/arch/x86/index.md
@@ -15,6 +15,8 @@ In order to add support for x86_64 the following assumptions are made:
* The high dword of pointers is always zero
* The reference implementation is qemu
* The CPU supports 1GiB hugepages
+* x86 payloads are loaded below 4GiB in physical memory and are jumped
+ to in *protected mode*
## Assuptions for all stages using the reference implementation
* 0-4GiB are identity mapped using 2MiB-pages as WB
@@ -47,7 +49,7 @@ At the moment *$n* is 4, which results in identity mapping the lower 4 GiB.
* Add assembly code for long mode - *DONE*
* Add assembly code for SMM - *DONE*
* Add assembly code for postcar stage - *DONE*
-* Add assembly code to return to protected mode - *TODO*
+* Add assembly code to return to protected mode - *DONE*
* Implement reference code for mainboard `emulation/qemu-q35` - *TODO*
## Future work