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From:   Ard Biesheuvel <ard.biesheuvel@linaro.org>
Date:   Fri, 6 Jul 2018 00:31:49 +0200
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Subject: Re: [PATCH v2 3/4] efi/arm: map UEFI memory map earlier on boot
To:     Will Deacon <will.deacon@arm.com>
Cc:     James Morse <james.morse@arm.com>,
        AKASHI Takahiro <takahiro.akashi@linaro.org>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        "Baicar, Tyler" <tbaicar@codeaurora.org>,
        Bhupesh Sharma <bhsharma@redhat.com>,
        Dave Young <dyoung@redhat.com>,
        Mark Rutland <mark.rutland@arm.com>,
        Al Stone <al.stone@linaro.org>,
        Graeme Gregory <graeme.gregory@linaro.org>,
        Hanjun Guo <hanjun.guo@linaro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Sudeep Holla <sudeep.holla@arm.com>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Kexec Mailing List <kexec@lists.infradead.org>
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On 5 July 2018 at 18:48, Will Deacon <will.deacon@arm.com> wrote:
> On Thu, Jul 05, 2018 at 12:02:15PM +0100, James Morse wrote:
>> On 05/07/18 10:43, AKASHI Takahiro wrote:
>> > On Wed, Jul 04, 2018 at 08:49:32PM +0200, Ard Biesheuvel wrote:
>> >> On 4 July 2018 at 19:06, Will Deacon <will.deacon@arm.com> wrote:
>> >>> On Tue, Jun 19, 2018 at 03:44:23PM +0900, AKASHI Takahiro wrote:
>> >>>> Since arm_enter_runtime_services() was modified to always create a virtual
>> >>>> mapping of UEFI memory map in the previous patch, it is now renamed to
>> >>>> efi_enter_virtual_mode() and called earlier before acpi_load_tables()
>> >>>> in acpi_early_init().
>> >>>>
>> >>>> This will allow us to use UEFI memory map in acpi_os_ioremap() to create
>> >>>> mappings of ACPI tables using memory attributes described in UEFI memory
>> >>>> map.
>>
>> >>> Hmm, this is ugly as hell. Is there nothing else we can piggy-back off?
>> >>> It's also fairly jarring that, on x86, efi_enter_virtual_mode() is called
>> >>> a few lines later, *after* acpi_early_init() has been called.
>>
>> >> Currently, there is a gap where we have already torn down the early
>> >> mapping and haven't created the definitive mapping of the UEFI memory
>> >> map. There are other reasons why this is an issue, and I recently
>> >> proposed [0] myself to address one of them
>>
>> >> Akashi-san, could you please confirm whether the patch below would be
>> >> sufficient for you? Apologies for going back and forth on this, but I
>> >> agree with Will that we should try to avoid warts like the one above
>> >> in generic code.
>> >>
>> >> [0] https://marc.info/?l=linux-efi&m=152930773507524&w=2
>> >
>> > I think that this patch will also work.
>> > Please drop my patch#2 and #3 if you want to pick up my patchset, Will.
>>
>> Patch 2 is what changes arm_enable_runtime_services() to map the efi memory map
>> before bailing out due to efi=noruntime.
>>
>> Without it, 'efi=noruntime' means no-acpi-tables.
>
> So it sounds like we want patch 2. Akashi, given that this series is only
> four patches, please can you send out a v3 with the stuff that should be
> reviewed and merged? Otherwise, there's a real risk we end up with breakage
> that goes unnoticed initially.
>

Yes, we want patches #1, #2 and #4, and this one can be replaced with
my patch above. Everything can be taken via the arm64 tree as far as I
am concerned.