From: "Michael S. Tsirkin" <mst@mellanox.co.il>
To: Andi Kleen <ak@suse.de>
Cc: discuss@x86-64.org, linux-kernel@vger.kernel.org
Subject: Re: [patch] Re: [discuss] f_ops flag to speed up compatible ioctls in linux kernel
Date: Sun, 12 Sep 2004 23:05:40 +0300 [thread overview]
Message-ID: <20040912200540.GA18013@mellanox.co.il> (raw)
In-Reply-To: <20040908145837.GD15444@wotan.suse.de>
Hello!
Quoting r. Andi Kleen (ak@suse.de) "Re: [patch] Re: [discuss] f_ops flag to speed up compatible ioctls in linux kernel":
> > So I wander what goes on here- the syscall returns a long but
> > libc cuts the high 32 bit?
>
> System calls are always long, otherwise the syscall exit code cannot
> check properly for signal restarts.
>
> glibc seems to indeed truncate.
>
> >
> > Now that I think about it,for compat if you start returning 0 in low
> > 32 bits you are unlike to get the effect you wanted ...
> > The ioctl_native could be changed but that would make it impossible
> > for compatible ioctls to just use the same pointer in both.
> >
> > So what do you think - should I make just the native ioctl a long,
> > or both, and document that the high 32 bit are cut in the compat call?
>
> both + document.
Given that libc truncates the high 32 bit, that compat call can only use
low 32 bit, I begin to really think its better to leave this as int
and avoid the whole issue.
Additional advantage is in keeping
the exact same interface as ioctl is that its easier to change a driver
to use this interface - just assign the call in field, no other changes.
MST
next prev parent reply other threads:[~2004-09-12 20:05 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-01 7:22 f_ops flag to speed up compatible ioctls in linux kernel Michael S. Tsirkin
2004-09-01 7:32 ` viro
2004-09-01 7:44 ` Michael S. Tsirkin
2004-09-01 7:47 ` Lee Revell
2004-09-01 8:19 ` Michael S. Tsirkin
2004-09-01 15:55 ` Roland Dreier
2004-09-01 18:02 ` Chris Wright
2004-09-01 18:12 ` Roland Dreier
2004-09-01 18:31 ` viro
2004-09-01 20:54 ` Roland Dreier
[not found] ` <20040901170800.K1924@build.pdx.osdl.net>
[not found] ` <20040901190122.L1924@build.pdx.osdl.net>
2004-09-02 3:46 ` Roland Dreier
2004-09-01 18:06 ` Bill Davidsen
2004-09-01 8:30 ` Arjan van de Ven
2004-09-01 15:40 ` [PATCH] fs/compat.c: rwsem instead of BKL around ioctl32_hash_table Roland Dreier
2004-09-01 23:27 ` Andrew Morton
2004-09-02 21:14 ` Andi Kleen
2004-09-02 22:26 ` Roland Dreier
2004-09-03 14:37 ` [discuss] " Andi Kleen
2004-09-03 14:55 ` Roland Dreier
2004-09-03 15:02 ` Andi Kleen
2004-09-03 8:00 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Andi Kleen
2004-09-07 10:40 ` Michael S. Tsirkin
2004-09-07 12:14 ` Andi Kleen
2004-09-07 13:45 ` Michael S. Tsirkin
2004-09-07 14:15 ` Andi Kleen
2004-09-07 14:25 ` Michael S. Tsirkin
2004-09-07 14:29 ` Andi Kleen
2004-09-07 14:37 ` Michael S. Tsirkin
2004-09-07 14:44 ` Andi Kleen
2004-09-07 14:45 ` Michael S. Tsirkin
2004-09-07 15:10 ` Andi Kleen
2004-09-07 18:16 ` Michael S. Tsirkin
2004-09-08 6:55 ` Andi Kleen
2004-09-08 14:28 ` [patch] " Michael S. Tsirkin
2004-09-08 14:38 ` Andi Kleen
2004-09-08 14:54 ` Michael S. Tsirkin
2004-09-08 14:58 ` Andi Kleen
2004-09-12 20:05 ` Michael S. Tsirkin [this message]
2004-09-15 13:19 ` [patch] Re: [discuss] " Michael S. Tsirkin
2004-09-07 21:36 ` Is FIOQSIZE compatible? ( was Re: f_ops flag to speed up compatible ioctls in linux kernel) Michael S. Tsirkin
2004-09-08 6:54 ` Andi Kleen
2004-09-07 15:03 ` [discuss] f_ops flag to speed up compatible ioctls in linux kernel Herbert Poetzl
2004-09-07 18:07 ` Michael S. Tsirkin
2004-09-09 13:54 ` Herbert Poetzl
2004-12-12 21:51 ` how to detect a 32 bit process on 64 bit kernel Michael S. Tsirkin
2004-12-12 22:01 ` Jan Engelhardt
2004-12-12 22:23 ` Christoph Hellwig
2004-12-13 19:50 ` Michael S. Tsirkin
2004-12-13 21:01 ` Jan Engelhardt
2004-12-13 21:32 ` Brian Gerst
2004-12-13 21:37 ` Michael S. Tsirkin
2004-12-12 22:37 ` Willy Tarreau
2004-12-12 23:30 ` Bongani Hlope
2004-12-14 7:28 ` Andi Kleen
2004-09-20 14:49 ` [patch] speed up ioctls in linux kernel Michael S. Tsirkin
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