linux-kernel - Re: [PATCH] powerpc: Kconfig: remove BE-only platforms from LE kernel build

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]

Date:	Wed, 9 Sep 2015 11:25:48 +0800
From:	Boqun Feng <boqun.feng@...il.com>
To:	Michael Ellerman <mpe@...erman.id.au>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Arnd Bergmann <arnd@...db.de>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Olof Johansson <olof@...om.net>,
	Geoff Levand <geoff@...radead.org>
Subject: Re: [PATCH] powerpc: Kconfig: remove BE-only platforms from LE
 kernel build

Hi Michael,

On Wed, Sep 09, 2015 at 12:26:44PM +1000, Michael Ellerman wrote:
> On Mon, 2015-09-07 at 07:58 +0800, Boqun Feng wrote:
> > diff --git a/arch/powerpc/platforms/cell/Kconfig b/arch/powerpc/platforms/cell/Kconfig
> > index 2f23133..808a904 100644
> > --- a/arch/powerpc/platforms/cell/Kconfig
> > +++ b/arch/powerpc/platforms/cell/Kconfig
> > @@ -25,7 +25,7 @@ config PPC_CELL_NATIVE
> >  
> >  config PPC_IBM_CELL_BLADE
> >  	bool "IBM Cell Blade"
> > -	depends on PPC64 && PPC_BOOK3S
> > +	depends on PPC64 && PPC_BOOK3S && CPU_BIG_ENDIAN
> 
> We end up saying this five times.
> 
> We already have PPC_BOOK3S_64 which captures the first two conditions, should
> we add a PPC_BOOK3S_64_BE which expresses it all?
> 

I'm not sure whether this is worth.. IMO, we add a config option only if

1.	we can use this config somewhere in the code, for example,
	"#ifdef CONFIG_XXX"
or

2.	we want to offer a option for users to choose.

PPC_BOOK3S_64_BE satisfies neither condition. Further more,
CONFIG_PPC64, CONFIG_PPC_BOOK3S and CONFIG_CPU_BIG_ENDIAN all are used
in some #ifdefs in current code. As a newbie of kernel, I'm happy to get
some knowledge like: "If I'm hacking PS3, then #ifndef CONFIG_PPC64 is
guaranteed to be false, so I can just ignore the code guarded by them".
But if we add a PPC_BOOK3S_64_BE, it will take a little more effort to
see this.

Regards,
Boqun

Download attachment "signature.asc" of type "application/pgp-signature" (474 bytes)