Re: efi_enabled(EFI_PARAVIRT) use

From	Shannon Zhao <shannon.zhao@linaro.org>
Newsgroups	linux.kernel
Subject	Re: efi_enabled(EFI_PARAVIRT) use
Date	2016-04-30 16:10 +0200
Message-ID	<rtDKO-Fh-25@gated-at.bofh.it> (permalink)
References	(1 earlier) <rtafL-1n2-1@gated-at.bofh.it> <rte02-4gY-25@gated-at.bofh.it> <rthKi-7Bl-7@gated-at.bofh.it> <rti3F-7N6-87@gated-at.bofh.it> <rtiGm-8rB-25@gated-at.bofh.it>
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On 2016年04月29日 23:37, Stefano Stabellini wrote:
> On Fri, 29 Apr 2016, Stefano Stabellini wrote:
>> On Fri, 29 Apr 2016, Matt Fleming wrote:
>>> On Fri, 29 Apr, at 11:34:45AM, Stefano Stabellini wrote:
>>>> On Fri, 29 Apr 2016, Ingo Molnar wrote:
>>>>> Also, it would be nice to have all things EFI in a single tree, the conflicts are 
>>>>> going to be painful! There's very little reason not to carry this kind of commit:
>>>>>
>>>>>  arch/arm/xen/enlighten.c           |  6 +++++
>>>>>  drivers/firmware/efi/arm-runtime.c | 17 +++++++++-----
>>>>>  drivers/firmware/efi/efi.c         | 45 ++++++++++++++++++++++++++++++++------
>>>>>  3 files changed, 56 insertions(+), 12 deletions(-)
>>>>>
>>>>> in the EFI tree.
>>>>
>>>> That's true. I'll drop this commit from xentip and let Matt pick it up
>>>> or request changes as he sees fit.
>>>
>>> One small change I think would be sensible to make is to expand
>>> EFI_PARAVIRT into a few more bits to clearly indicate the quirks on
>>> Xen, and in the process, to delete EFI_PARAVIRT.
>>>
>>> That should address Ingo's major concern, and also make it much easier
>>> to rework the code in a piecemeal fashion.
>>>
>>> Could somebody enumerate the things that make Xen (dom0) different on
>>> arm* compared with bare metal EFI boot? The list I made for x86 was,
>>>
>>>   1. Has no EFI memory map
>>>   2. Runtime regions do not need to be mapped
>>>   3. Cannot call SetVirtualAddressMap()
>>>   4. /sys/firmware/efi/fw_vendor is invisible
>>>
>>> The first maps to not setting EFI_MEMMAP, the second to not setting
>>> EFI_RUNTIME. If we add EFI_ALREADY_VIRTUAL and EFI_FW_VENDOR_INVISIBLE
>>> to efi.flags that should cover everything on x86. Does arm* require
>>> anything else?
>>
>> Xen on ARM is different, the impact should be limited:
>>
>> - there are no BootServices (ExitBootServices has already been called)
>> - RuntimeServices go via hypercalls
>>
>> The UEFI memory map is still available at an address specified on device
>> tree like on native, but the compatibility string is different
>> ("xen,uefi-mmap-start") to clarify that we are booting on Xen rather
>> than native.
>>
>> That's pretty much it, Shannon please confirm.
> 
> This is to say that Xen on ARM might only need EFI_RUNTIME.
> 
Yes, it needs EFI_RUNTIME_SERVICES.

Thanks,
-- 
Shannon

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linux-next: manual merge of the xen-tip tree with the tip tree Stephen Rothwell <sfr@canb.auug.org.au> - 2016-04-29 06:30 +0200
  Re: efi_enabled(EFI_PARAVIRT) use Ingo Molnar <mingo@kernel.org> - 2016-04-29 08:40 +0200
    Re: efi_enabled(EFI_PARAVIRT) use Borislav Petkov <bp@alien8.de> - 2016-04-29 10:30 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-29 11:30 +0200
    Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 12:40 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Ingo Molnar <mingo@kernel.org> - 2016-04-29 12:50 +0200
      Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-29 16:40 +0200
        Re: efi_enabled(EFI_PARAVIRT) use Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2016-04-29 17:00 +0200
          Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-04-30 16:20 +0200
            Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-04-30 22:50 +0200
              Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-05-01 05:30 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-01 15:30 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-05-01 16:40 +0200
                Re: efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-02 12:50 +0200
                Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Shannon Zhao <zhaoshenglong@huawei.com> - 2016-05-03 03:50 +0200
                Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Matt Fleming <matt@codeblueprint.co.uk> - 2016-05-04 13:40 +0200
            Re: [Xen-devel] efi_enabled(EFI_PARAVIRT) use Shannon Zhao <zhaoshenglong@huawei.com> - 2016-05-03 11:20 +0200
        Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 17:00 +0200
          Re: efi_enabled(EFI_PARAVIRT) use Stefano Stabellini <sstabellini@kernel.org> - 2016-04-29 17:40 +0200
            Re: efi_enabled(EFI_PARAVIRT) use Shannon Zhao <shannon.zhao@linaro.org> - 2016-04-30 16:10 +0200

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