diff options
| author | Patrick Rudolph <siro@das-labor.org> | 2018-12-09 10:48:59 +0100 |
|---|---|---|
| committer | Patrick Rudolph <siro@das-labor.org> | 2020-08-19 09:06:43 +0000 |
| commit | e563815e059ef5881a42e6f8b37094783771d5a7 (patch) | |
| tree | 7641211d03c315d37176717cbf37588ec4ebd38b /Documentation/arch/x86 | |
| parent | ad7b2e23ab5954f150a4b2f62378f1e7133e56c9 (diff) | |
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/x86')
| -rw-r--r-- | Documentation/arch/x86/index.md | 4 |
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 |