linux-kernel - Re: [PATCH] ubi: kill homegrown endian macros

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:	Sat, 19 May 2007 14:24:36 +0200
From:	Segher Boessenkool <segher@...nel.crashing.org>
To:	David Woodhouse <dwmw2@...radead.org>
Cc:	Matthieu CASTET <castet.matthieu@...e.fr>,
	"John Anthony Kazos Jr." <jakj@...-k-j.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ubi: kill homegrown endian macros

>> It's not the compiler who decides -- struct layout is
>> dictated by the ABI you're compiling for.
>
> This is true in the case of externally-visible stuff. I think the
> compiler is permitted to violate the ABI for purely unit-internal 
> things
> if it makes sense though, isn't it?

Sure.  It isn't "violating the ABI" in that case though,
to be perfectly clear.

> Besides, in the case of the Linux kernel the ABI in question could be
> one of many. It could even be a new one which was added a couple of
> weeks ago, and which I had no _chance_ of considering.

Of course.

> The rule stands -- empirical testing of what the compiler will do isn't
> usually the right answer.

It is *never* the right answer.  You should always write
your code so that it will do the right thing no matter
what the compiler decides to do to it.


Segher

-
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/