linux-kernel - RE: [PATCH] x86/efi: Don't unmap EFI boot services code/data regions for EFI_OLD_MEMMAP and EFI_MIXED

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Date:   Fri, 28 Dec 2018 21:27:55 +0000
From:   "Prakhya, Sai Praneeth" <sai.praneeth.prakhya@...el.com>
To:     Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Ingo Molnar <mingo@...nel.org>
CC:     linux-efi <linux-efi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        the arch/x86 maintainers <x86@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: RE: [PATCH] x86/efi: Don't unmap EFI boot services code/data
 regions for EFI_OLD_MEMMAP and EFI_MIXED_MODE

> > Acked-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> >
> > with the sidenote that I won't be able to test this myself until
> > monday at the earliest.
> 
> OK, so I have tested both efi=old_map and mixed mode before and after
> applying this patch, using QEMU/KVM with 64-bit and 32-bit builds of OVMF
> [respectively]
> 
> efi=old_map is indeed broken before and needs this patch.
> 
> Mixed mode works just fine both before and after applying the patch, but I
> suggest we keep this patch as-is and address mixed mode later if needed (I
> spotted a couple of things in the boot log that may need some attention but I'm
> not sure if the issue is in Linux or in OVMF)

Thanks for testing this Ard.

For testing Mixed mode, I have used QEMU/KVM with 64-bit and 32-bit OVMF 
and mixed mode is broken for me without this patch.

I am using an older OVMF build and probably that might be the reason for us seeing 
different behaviors. Also, kernel config file might have some role to play.. I guess.

Regards,
Sai