linux-kernel - Re: [REGRESSION] "efi: efistub: Convert into static library" and preparation patches

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Message-ID: <540819A8.7060205@canonical.com>
Date:	Thu, 04 Sep 2014 09:50:00 +0200
From:	Maarten Lankhorst <maarten.lankhorst@...onical.com>
To:	Matt Fleming <matt@...sole-pimps.org>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>
CC:	"H. Peter Anvin" <hpa@...or.com>, Ulf Winkelvos <ulf@...kelvos.de>,
	Matt Fleming <matt.fleming@...el.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Seth Forshee <seth.forshee@...onical.com>,
	Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [REGRESSION] "efi: efistub: Convert into static library" and
 preparation patches

Op 04-09-14 om 09:40 schreef Matt Fleming:
> On Thu, 04 Sep, at 08:47:57AM, Ard Biesheuvel wrote:
>> So how about we:
>> - add ASSERT(_got == _egot, "GOT entries not supported in
>> boot/compressed") to the linker script
>> - #define __nogotentry __attribute__((visibility(hidden))) somewhere
>> in compiler.h or wherever else it belongs
>> - add the __nogotentry qualifiers to each extern that requires it,
>> which is currently:
>> early_serial_base
>> efi_early
>> free_mem_end_ptr
>> free_mem_ptr
>> real_mode
>> - get rid of the fixup code in assembly
>  
> Seems fine to me since it was Peter who introduced the GOT fixup asm
> code in the first place.
>
>> Any idea what the oldest GCC is we should support?
> I'm pretty sure we still support GCC 3.x.x. The symbol visibility
> support was added in GCC 4.x right?
>
gcc 3.3.6 has documented visibility at least.

https://gcc.gnu.org/onlinedocs/gcc-3.3.6/gcc/Function-Attributes.html#Function-Attributes

I couldn't find it in earlier manuals, but grepping through gcc 3.0.4 source code shows that it would appear to be supported there too.

~Maarten

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