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From:   Ard Biesheuvel <ardb@kernel.org>
Date:   Wed, 29 Apr 2020 21:48:04 +0200
Message-ID: <CAMj1kXEwxqPA7t8N+A25+VnxO4opBdM6__An=Er-Yh+QLOZ3Jw@mail.gmail.com>
Subject: Re: [PATCH 03/10] efi/x86: Use pr_efi_err for error messages
To:     Joe Perches <joe@perches.com>
Cc:     Arvind Sankar <nivedita@alum.mit.edu>,
        linux-efi <linux-efi@vger.kernel.org>, X86 ML <x86@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Wed, 29 Apr 2020 at 21:47, Joe Perches <joe@perches.com> wrote:
>
> On Wed, 2020-04-29 at 20:59 +0200, Ard Biesheuvel wrote:
> > On Wed, 29 Apr 2020 at 20:57, Joe Perches <joe@perches.com> wrote:
> > > On Wed, 2020-04-29 at 20:49 +0200, Ard Biesheuvel wrote:
> > > > On Wed, 29 Apr 2020 at 20:47, Joe Perches <joe@perches.com> wrote:
> > > > > Looking at code for efi_printk -> efi_char16_printk,
> > > > > it's somewhat difficult to see where the "output_string"
> > > > > function pointer is set.  Any clue?
> > > > It is set by the firmware.
> > >
> > > Sure, where in the code though?
> > >
> >
> > In which code? The firmware code?
>
> I presume it's set from a struct received from hardware/firmware
> somewhere in drivers/firmware/efi, but it doesn't seem clear where.
>

It is a field in the EFI system table, which we dereference directly.