Messages in this thread | | | Date | Mon, 22 Aug 2016 11:58:50 +0200 | From | Lukas Wunner <> | Subject | Re: [PATCH 0/6] Apple device properties |
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On Thu, Aug 18, 2016 at 09:34:33PM +0100, Matt Fleming wrote: > On Mon, 15 Aug, at 06:13:58PM, Lukas Wunner wrote: > > But I would like to understand the "cannot jump through pointers at > > runtime" argument because the binary code looks to me like it should > > work on 32 bit. I guess I must be missing something obvious? > > Ah no, I forgot that efi_boot_services_{32,64}_t doesn't contain > pointers - it contains u32/u64 objects. So yeah, your patch looks > fine. > > It does trigger the following warnings when building for i386 though, > > In file included from /dev/shm/mfleming/git/efi/drivers/firmware/efi/libstub/efi-stub-helper.c:14:0: > /dev/shm/mfleming/git/efi/drivers/firmware/efi/libstub/efi-stub-helper.c: In function ???efi_get_memory_map???: > /dev/shm/mfleming/git/efi/arch/x86/include/asm/efi.h:205:3: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] > ((efi_boot_services_64_t *)__efi_early()->boot_services)->f : \ > ^
Right, sorry, I didn't compile-test that version on x86_32.
I'm sending out a new version now which compiles cleanly in all three cases (x86_32, x86_64 with and without mixed-mode), works fine on my 64-bit EFI and the 32-bit code at least *looks* okay when disassembled.
By the way, arch/x86/Kconfig says that "it is not possible to boot a mixed-mode enabled kernel via the EFI boot stub - a bootloader that supports the EFI handover protocol must be used".
Is this still correct? With all the mixed-mode support in head_64.S and eboot.c, I'm wondering what's missing?
Thanks,
Lukas
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