From: Andi Kleen <ak@suse.de>
To: Pavel Machek <pavel@suse.cz>
Cc: "David S. Miller" <davem@redhat.com>,
linux-kernel@vger.kernel.org, torvalds@transmeta.com
Subject: Re: share COMPATIBLE_IOCTL()s across architectures
Date: 20 Mar 2003 21:24:49 +0100 [thread overview]
Message-ID: <1048191889.15338.189.camel@averell> (raw)
In-Reply-To: <20030320193212.GA312@elf.ucw.cz>
On Thu, 2003-03-20 at 20:32, Pavel Machek wrote:
> Hi!
>
> > This patche moves common COMPATIBLE_IOCTLs to
> > include/linux/compat_ioctl.h, enabling pretty nice cleanups:
> >
> > Please be careful. For anything non-trivial there can be major
> > differences between compat layers.
>
> I'm trying to be carefull. How common are ioctls that are
> COMPATIBLE_IOCTL(foo) on one arch, but not on another? So far I tried
> to decide, and mostly decided that one architecture was simply
> missing...
The only issue I'm aware of are structures with long long. IA64 and
x86-64 are special in that long long has a different alignmnet in 32bit
and 64bit (4 bytes in 32bit, 8 bytes in 64bit). All the other archs with
compat code have always 8 byte alignment. This means if sparc64 doesn't
do a conversion, but x86-64 does you cannot put it into the COMPAT_IOCTL
list. Make sure you only use the common set.
Fortunately long long is not that common and many uses of it are already
8 byte aligned, but not all are.
-Andi
next prev parent reply other threads:[~2003-03-20 20:13 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-19 23:21 share COMPATIBLE_IOCTL()s across architectures Pavel Machek
2003-03-20 0:01 ` David S. Miller
2003-03-20 19:32 ` Pavel Machek
2003-03-20 20:24 ` Andi Kleen [this message]
2003-03-21 10:21 ` Pavel Machek
[not found] <20030319232157.GA13415@elf.ucw.cz.suse.lists.linux.kernel>
2003-03-20 0:08 ` Andi Kleen
2003-03-20 19:33 ` Pavel Machek
2003-03-20 20:26 ` Andi Kleen
2003-03-21 10:24 ` Pavel Machek
[not found] <20030320001013$67af@gated-at.bofh.it>
[not found] ` <20030320001013$68b4@gated-at.bofh.it>
2003-03-20 1:35 ` Arnd Bergmann
2003-03-20 2:38 ` Andi Kleen
2003-03-20 10:30 ` Arnd Bergmann
2003-03-20 19:35 ` Pavel Machek
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