On 2015/9/14 17:09, Ard Biesheuvel wrote: > On 14 September 2015 at 10:42, Shannon Zhao <zhaoshenglong@xxxxxxxxxx> wrote: > [..] > >> >> It only needs to apply following patch to fix a bug in Linux kernel when >> mapping EFI_MEMORY_RUNTIME memory. >> > > Could you explain why you think efi_virtmap_init() should fail if > there are no EFI_MEMORY_RUNTIME regions? > My understanding is that if there are no EFI_MEMORY_RUNTIME regions, it means we can't use runtime services and should not set the bit EFI_RUNTIME_SERVICES of efi.flags. But if efi_virtmap_init() return true, the bit will be set. > The absence of such regions is allowed by the spec, so > efi_virtmap_init() is correct imo to return success. > Sorry, not well know about the spec. Could you point out where the spec says this? > If you are trying to work around the issue where Xen does not expose > any Runtime Services regions, there is simply no way to do that and be > still UEFI compliant. I have suggested before that we should perhaps > tolerate this anyway, by considering the case where the EFI System > Table has a NULL runtime services pointer. But rigging > efi_virtmap_init() like this is really not the way to achieve that. > -- Shannon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
