linux-kernel - RE: [PATCH 4/5] efi: Export Runtime Configuration Interface table to sysfs

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Date:   Tue, 1 Oct 2019 13:20:46 +0000
From:   <Mario.Limonciello@...l.com>
To:     <ard.biesheuvel@...aro.org>, <geert@...ux-m68k.org>
CC:     <Narendra.K@...l.com>, <linux-efi@...r.kernel.org>,
        <mingo@...nel.org>, <tglx@...utronix.de>,
        <linux-kernel@...r.kernel.org>, <james.morse@....com>,
        <tanxiaofei@...wei.com>
Subject: RE: [PATCH 4/5] efi: Export Runtime Configuration Interface table to
 sysfs

> -----Original Message-----
> From: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> Sent: Tuesday, October 1, 2019 4:42 AM
> To: Geert Uytterhoeven
> Cc: K, Narendra; linux-efi; Ingo Molnar; Thomas Gleixner; Linux Kernel Mailing List;
> James Morse; Limonciello, Mario; Xiaofei Tan
> Subject: Re: [PATCH 4/5] efi: Export Runtime Configuration Interface table to sysfs
> 
> 
> [EXTERNAL EMAIL]
> 
> On Tue, 1 Oct 2019 at 11:03, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
> >
> > Hi Ard,
> >
> > On Tue, Oct 1, 2019 at 10:54 AM Ard Biesheuvel
> > <ard.biesheuvel@...aro.org> wrote:
> > > On Tue, 1 Oct 2019 at 10:51, Geert Uytterhoeven <geert@...ux-m68k.org>
> wrote:
> > > > On Mon, Aug 12, 2019 at 5:07 PM Ard Biesheuvel
> > > > <ard.biesheuvel@...aro.org> wrote:
> > > > > From: Narendra K <Narendra.K@...l.com>
> > > > >
> > > > > System firmware advertises the address of the 'Runtime
> > > > > Configuration Interface table version 2 (RCI2)' via
> > > > > an EFI Configuration Table entry. This code retrieves the RCI2
> > > > > table from the address and exports it to sysfs as a binary
> > > > > attribute 'rci2' under /sys/firmware/efi/tables directory.
> > > > > The approach adopted is similar to the attribute 'DMI' under
> > > > > /sys/firmware/dmi/tables.
> > > > >
> > > > > RCI2 table contains BIOS HII in XML format and is used to populate
> > > > > BIOS setup page in Dell EMC OpenManage Server Administrator tool.
> > > > > The BIOS setup page contains BIOS tokens which can be configured.
> > > > >
> > > > > Signed-off-by: Narendra K <Narendra.K@...l.com>
> > > > > Reviewed-by: Mario Limonciello <mario.limonciello@...l.com>
> > > > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@...aro.org>
> > > >
> > > > Thanks, this is now commit 1c5fecb61255aa12 ("efi: Export Runtime
> > > > Configuration Interface table to sysfs").
> > > >
> > > > > --- a/drivers/firmware/efi/Kconfig
> > > > > +++ b/drivers/firmware/efi/Kconfig
> > > > > @@ -180,6 +180,19 @@ config RESET_ATTACK_MITIGATION
> > > > >           have been evicted, since otherwise it will trigger even on clean
> > > > >           reboots.
> > > > >
> > > > > +config EFI_RCI2_TABLE
> > > > > +       bool "EFI Runtime Configuration Interface Table Version 2 Support"
> > > > > +       help
> > > > > +         Displays the content of the Runtime Configuration Interface
> > > > > +         Table version 2 on Dell EMC PowerEdge systems as a binary
> > > > > +         attribute 'rci2' under /sys/firmware/efi/tables directory.
> > > > > +
> > > > > +         RCI2 table contains BIOS HII in XML format and is used to populate
> > > > > +         BIOS setup page in Dell EMC OpenManage Server Administrator tool.
> > > > > +         The BIOS setup page contains BIOS tokens which can be configured.
> > > > > +
> > > > > +         Say Y here for Dell EMC PowerEdge systems.
> > > >
> > > > A quick Google search tells me these are Intel Xeon.
> > > > Are arm/arm64/ia64 variants available, too?
> > > > If not, this should be protected by "depends on x86" ("|| COMPILE_TEST"?).
> > >
> > > The code in question is entirely architecture agnostic, and defaults
> > > to 'n', so I am not convinced this is needed. (It came up in the
> > > review as well)
> >
> > "make oldconfig" still asks me the question on e.g. arm64, where it is
> > irrelevant, until arm64 variants of the hardware show up.
> >
> > So IMHO it should have "depends on X86 || COMPILE_TEST".
> >
> 
> Fair enough. I am going to send out a bunch of EFI fixes this week, so
> I'll accept a patch that makes the change above.

Is it really a problem to just say n?

I think this seems like a needless change that would slow down adoption of
!x86 if Dell EMC PowerEdge systems did start going that route, especially
when it comes to distributions that move glacially slow with picking up new
kernel code.