linux-kernel - Re: [tip:efi/core] efibc: Add EFI Bootloader Control module

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Date:	Fri, 29 Apr 2016 11:53:56 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	jeremy.compostella@...el.com, stefan.stanacar@...el.com,
	matt@...eblueprint.co.uk, peterz@...radead.org,
	linux-kernel@...r.kernel.org, tglx@...utronix.de, hpa@...or.com,
	bp@...en8.de, ard.biesheuvel@...aro.org
Cc:	linux-tip-commits@...r.kernel.org
Subject: Re: [tip:efi/core] efibc: Add EFI Bootloader Control module


* tip-bot for Compostella, Jeremy <tipbot@...or.com> wrote:

> Commit-ID:  06f7d4a1618dbb086e738c93cd1ef416ab01027d
> Gitweb:     http://git.kernel.org/tip/06f7d4a1618dbb086e738c93cd1ef416ab01027d
> Author:     Compostella, Jeremy <jeremy.compostella@...el.com>
> AuthorDate: Mon, 25 Apr 2016 21:06:57 +0100
> Committer:  Ingo Molnar <mingo@...nel.org>
> CommitDate: Thu, 28 Apr 2016 11:34:02 +0200
> 
> efibc: Add EFI Bootloader Control module
> 
> This module installs a reboot callback, such that if reboot() is invoked
> with a string argument NNN, "NNN" is copied to the "LoaderEntryOneShot"
> EFI variable, to be read by the bootloader.

>  drivers/firmware/efi/Kconfig  |  15 +++++++
>  drivers/firmware/efi/Makefile |   1 +
>  drivers/firmware/efi/efibc.c  | 101 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/efi.h           |   4 ++
>  4 files changed, 121 insertions(+)

So this bloated things a bit on 32-bit x86 allyesconfig kernels, we now have this 
new warning:

  drivers/firmware/efi/efibc.c:53:1: warning: the frame size of 2256 bytes is larger than 1024 bytes [-Wframe-larger-than=]

2K of stack use for a function is quite excessive, can we improve the stack 
footprint of this code?

Thanks,

	Ingo