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    SubjectRe: [PATCH][EFI] Run EFI in physical mode
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    No, it should not be dynamic; rather we should unify all the users who need a 1:1 map and just keep that page table set around.

    "huang ying" <huang.ying.caritas@gmail.com> wrote:

    >On Sat, Aug 14, 2010 at 3:18 AM, Takao Indoh <indou.takao@jp.fujitsu.com> wrote:
    >> diff -Nurp linux-2.6.35.org/arch/x86/kernel/efi_64.c linux-2.6.35/arch/x86/kernel/efi_64.c
    >> --- linux-2.6.35.org/arch/x86/kernel/efi_64.c   2010-08-01 18:11:14.000000000 -0400
    >> +++ linux-2.6.35/arch/x86/kernel/efi_64.c       2010-08-13 14:39:25.819105004 -0400
    >> @@ -39,7 +39,9 @@
    >>  #include <asm/fixmap.h>
    >>
    >>  static pgd_t save_pgd __initdata;
    >> -static unsigned long efi_flags __initdata;
    >> +static unsigned long efi_flags;
    >> +static pgd_t efi_pgd[PTRS_PER_PGD] __page_aligned_bss;
    >> +static unsigned long save_cr3;
    >>
    >>  static void __init early_mapping_set_exec(unsigned long start,
    >>                                          unsigned long end,
    >> @@ -98,6 +100,19 @@ void __init efi_call_phys_epilog(void)
    >>        early_runtime_code_mapping_set_exec(0);
    >>  }
    >>
    >> +void efi_call_phys_prelog_in_physmode(void)
    >> +{
    >> +       local_irq_save(efi_flags);
    >> +       save_cr3 = read_cr3();
    >> +       write_cr3(virt_to_phys(efi_pgd));
    >> +}
    >> +
    >> +void efi_call_phys_epilog_in_physmode(void)
    >> +{
    >> +       write_cr3(save_cr3);
    >> +       local_irq_restore(efi_flags);
    >> +}
    >
    >efi_flags and save_cr3 should be per-CPU, because they now will be
    >used after SMP is enabled.
    >
    >efi_pgd should be dynamically allocated instead of statically
    >allocated, because EFI may be not enabled on some platform.
    >
    >And I think it is better to unify early physical mode with run-time
    >physical mode. Just allocate the page table with early page allocator
    >(lmb?).
    >
    >Best Regards,
    >Huang Ying
    >

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