linux-kernel - Re: [PATCH v2 3/4] efi/arm: map UEFI memory map earlier on boot

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Date:   Fri, 6 Jul 2018 14:37:59 +0100
From:   Will Deacon <will.deacon@....com>
To:     AKASHI Takahiro <takahiro.akashi@...aro.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Baicar, Tyler" <tbaicar@...eaurora.org>,
        Bhupesh Sharma <bhsharma@...hat.com>,
        Dave Young <dyoung@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Al Stone <al.stone@...aro.org>,
        Graeme Gregory <graeme.gregory@...aro.org>,
        Hanjun Guo <hanjun.guo@...aro.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Kexec Mailing List <kexec@...ts.infradead.org>
Subject: Re: [PATCH v2 3/4] efi/arm: map UEFI memory map earlier on boot

Hi Akashi,

On Fri, Jul 06, 2018 at 10:33:13AM +0900, AKASHI Takahiro wrote:
> On Fri, Jul 06, 2018 at 09:42:28AM +0900, AKASHI Takahiro wrote:
> > I almost believed that my patch#2 was just a preparatory one for patch#3
> > where arm_enable_runtime_services() is moved aggressively forward.
> > But acpi_os_ioremap() is not a __init function and I can now agree to
> > keeping patch#2.
> > 
> > Meanwhile, the consequent code with Ard's patch would look like:
> > ---8<---
> > static int __init arm_enable_runtime_services(void)
> > {
> >         ...
> >         efi_memmap_unmap();
> > 
> >         mapsize = efi.memmap.desc_size * efi.memmap.nr_map;
> > 
> >         if (efi_memmap_init_late(efi.memmap.phys_map, mapsize)) {
> >                 pr_err("Failed to remap EFI memory map\n");
> >                 return 0;
> >         }
> >         ...
> > }
> > --->8---
> > It seems to me that it makes no sense.
> 
> Oops, it does. Comments at efi_memmap_init_late() say:
> ---8<---
>  * The reason there are two EFI memmap initialisation
>  * (efi_memmap_init_early() and this late version) is because the
>  * early EFI memmap should be explicitly unmapped once EFI
>  * initialisation is complete as the fixmap space used to map the EFI
>  * memmap (via early_memremap()) is a scarce resource.
> --->8---
> 
> > Is it okay to take them out?
> 
> Never mind.

I'm struggling with your monologue...

Please can you send a v3 of the series, containing the patches that you
think are necessary, along with the Acks you've collected?

Thanks,

Will