Messages in this thread | | | Date | Sat, 16 Apr 2022 09:32:01 +0800 | Subject | Re: [PATCH v2 0/9] introduce mirrored memory support for arm64 | From | mawupeng <> |
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在 2022/4/14 18:22, Ard Biesheuvel 写道: > On Thu, 14 Apr 2022 at 11:54, Wupeng Ma <mawupeng1@huawei.com> wrote: >> >> From: Ma Wupeng <mawupeng1@huawei.com> >> >> Commit b05b9f5f9dcf ("x86, mirror: x86 enabling - find mirrored memory ranges") >> introduced mirrored memory support for x86. This support rely on UEFI to >> report mirrored memory address ranges. See UEFI 2.5 spec pages 157-158: >> >> http://www.uefi.org/sites/default/files/resources/UEFI%202_5.pdf >> >> Memory mirroring is a technique used to separate memory into two separate >> channels, usually on a memory device, like a server. In memory mirroring, >> one channel is copied to another to create redundancy. This method makes >> input/output (I/O) registers and memory appear with more than one address >> range because the same physical byte is accessible at more than one >> address. Using memory mirroring, higher memory reliability and a higher >> level of memory consolidation are possible. >> >> Arm64 can support this too. So mirrored memory support is added to support >> arm64. >> >> Efi_fake_mem is used for testing mirrored features and will not be used in >> production environment. This test features can fake memory's attribute >> values. >> >> The reason why efi_fake_mem support is put first is that memory's attribute >> is reported by BIOS which is hard to simulate. With this support, any arm64 >> machines with efi support can easily test mirrored features. >> >> The main purpose of this patchset is to introduce mirrored support for >> arm64 and we have already fixed the problems we had which is shown in >> patch #5 to patch #7 and try to bring total isolation in patch #8 which >> will disable mirror feature if kernelcore is not specified. >> >> In order to test this support in arm64: >> - patch this patchset >> - add efi_fake_mem=8G@0:0x10000 in kernel parameter to simulate mirrored >> memroy between phy addr 0-8G. >> - add kernelcore=mirror in kernel parameter >> - start you kernel >> > > As I explained before: > > - NAK to EFI fake_mem support on arm64
fake_mem support on arm64 will be removed in subsequent version.
> - NAK to the whole series until you come up with a proposal on how to > locate the static kernel image itself into more reliable memory, as > there is really no point to any of this otherwise.
Sorry I am not familiar with this, as you metioned before,
> you have to iterate over the memory map and look for regions with > the desired attribute, and allocate those pages explicitly.
Do you mean this is x86, commit c05cd79750fb ("x86/boot/KASLR: Prefer mirrored memory regions for the kernel physical address"). I will do some research.
> I'd prefer to implement this in the bootloader, and only add minimal > logic to the stub to respect the placement of the kernel by the loader > if the loader signals it to do so.
Does this bootloader refer to grub and then add minimal logic to arm64-stub.c?
What is the loader signal? System exists mirrored memory reported by uefi?
Thanks for reviewing, sorry for my ignorance on this.
> .
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