linux-kernel - Re: [PATCH v2] arch: Kconfig: Let all little endian architectures define CPU_LITTLE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <53EB0AF6.6060208@zytor.com>
Date:	Tue, 12 Aug 2014 23:51:34 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Chen Gang <gang.chen.5i5j@...il.com>,
	Sam Ravnborg <sam@...nborg.org>
CC:	Arnd Bergmann <arnd@...db.de>, akpm@...ux-foundation.org,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Jean Delvare <jdelvare@...e.de>, linux@....linux.org.uk,
	catalin.marinas@....com, will.deacon@....com, msalter@...hat.com,
	a-jacquiot@...com, tony.luck@...el.com, fenghua.yu@...el.com,
	tglx@...utronix.de, mingo@...hat.com, x86@...nel.org,
	linux-arm-kernel@...ts.infradead.org, linux-c6x-dev@...ux-c6x.org,
	linux-ia64@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-arch@...r.kernel.org
Subject: Re: [PATCH v2] arch: Kconfig: Let all little endian architectures
 define CPU_LITTLE_ENDIAN explicitly

On 08/12/2014 10:32 PM, Chen Gang wrote:
> 
> Yeah, we need.
> 
>> The solution you suggest assumes that an arch is either little or big endian.
>> But we cannot ignore the hybriads that can do both.
>>
> 
> For the architectures which can do both, for me, they are: sh, powerpc,
> m32r, and mips (may mark CPU_LITTLE_ENDIAN), also are: arm/arm64, and
> c6x (may mark !CPU_BIG_ENDIAN).
> 
> For the architectures which only support little endian: x86, and ia64.
> 
> The left, I assumes they are big endian (no any 'ENDIAN' can be found
> in their Kconfig files). In my memory, except related with Intel, all
> are (or support) big endian.
> 

I'm quite certain that is wrong.  From memory, for example, I believe
CRIS is littleendian, and sure enough:

: tazenda 103 ; less arch/cris/include/uapi/asm/byteorder.h
#ifndef _CRIS_BYTEORDER_H
#define _CRIS_BYTEORDER_H

#include <linux/byteorder/little_endian.h>

#endif

As far as I know, endianism is always a compile-time option on Linux, so
we should be able to relatively easily define the architecture so that
we either have hardwired littleendian, bigendian, or prompt.

	-hpa

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/