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Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions

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On 09/27/2015 12:06 AM, Ingo Molnar wrote:
> 
> * Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> 
>>> If we allocate the EFI runtime as a single virtual memory block then issues 
>>> like rounding between sections does not even come up as a problem: we map the 
>>> original offsets and sizes byte by byte.
>>
>> Well, by that reasoning, we should not call SetVirtualAddressMap() in the first 
>> place, and just use the 1:1 mapping UEFI uses natively. This is more than 
>> feasible on arm64, and I actually fought hard against using 
>> SetVirtualAddressMap() at all, but I was overruled by others. I think this is 
>> also trivially possible on X64, since the 1:1 mapping is already active 
>> alongside the VA mapping.
> 
> Could we please re-list all the arguments pro and contra of 1:1 physical mappings, 
> in a post that also explains the background so that more people can chime in, not 
> just people versed in EFI internals? It's very much possible that a bad decision 
> was made.
> 

Pro: by far the sanest way to map the UEFI tables.
Con: doesn't actually work (breaks on several known platforms.)

	-hpa


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[PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions Matt Fleming <matt@codeblueprint.co.uk> - 2015-09-26 00:10 +0200
  Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Ingo Molnar <mingo@kernel.org> - 2015-09-26 08:10 +0200
    Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-09-26 09:10 +0200
      Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Ingo Molnar <mingo@kernel.org> - 2015-09-27 09:10 +0200
        Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Borislav Petkov <bp@alien8.de> - 2015-09-27 12:20 +0200
          Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Ingo Molnar <mingo@kernel.org> - 2015-09-28 08:30 +0200
          Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Dave Young <dyoung@redhat.com> - 2015-09-29 11:40 +0200
            Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Borislav Petkov <bp@alien8.de> - 2015-09-29 12:30 +0200
          Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Matt Fleming <matt@codeblueprint.co.uk> - 2015-09-29 16:40 +0200
            Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions "H. Peter Anvin" <hpa@zytor.com> - 2015-09-30 03:00 +0200
              Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Borislav Petkov <bp@alien8.de> - 2015-09-30 10:40 +0200
        Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions "H. Peter Anvin" <hpa@zytor.com> - 2015-09-30 03:10 +0200
          Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions Andy Lutomirski <luto@amacapital.net> - 2015-09-30 03:20 +0200
            Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions "H. Peter Anvin" <hpa@zytor.com> - 2015-09-30 03:20 +0200
            Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME regions Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2015-09-30 06:30 +0200
          Re: [PATCH 2/2] arm64/efi: Don't pad between EFI_MEMORY_RUNTIME  regions Ingo Molnar <mingo@kernel.org> - 2015-10-01 12:50 +0200
  [tip:core/urgent] arm64/efi:   Fix boot crash by not padding between EFI_MEMORY_RUNTIME regions tip-bot for Ard Biesheuvel <tipbot@zytor.com> - 2015-10-01 15:00 +0200

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