From: Arjan van de Ven <arjanv@redhat.com>
To: linux-kernel@vger.kernel.org
Cc: discuss@x86-64.org
Subject: Re: f_ops flag to speed up compatible ioctls in linux kernel
Date: Wed, 01 Sep 2004 10:30:18 +0200 [thread overview]
Message-ID: <1094027417.2947.1.camel@laptop.fenrus.com> (raw)
In-Reply-To: <20040901072245.GF13749@mellanox.co.il>
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On Wed, 2004-09-01 at 09:22, Michael S. Tsirkin wrote:
> Hello!
> Currently, on the x86_64 architecture, its quite tricky to make
> a char device ioctl work for an x86 executables.
> In particular,
> 1. there is a requirement that ioctl number is unique -
> which is hard to guarantee especially for out of kernel modules
well... external modules thus should be really really careful with
ioctls then and not embrace and extend too much but just use existing
ones instead when reasonable
> 2. there's a performance huge overhead for each compat call - there's
> a hash lookup in a global hash inside a lock_kernel -
> and I think compat performance *is* important.
such is life
>
> Further, adding a command to the ioctl suddenly requires changing
> two places - registration code and ioctl itself.
adding ioctls SHOULD be painful. Really painful. It's similar to adding
syscalls; you'll have to keep compatibility basically forever so adding
should not be an easy thing.
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next prev parent reply other threads:[~2004-09-01 8:34 UTC|newest]
Thread overview: 73+ 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 [this message]
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
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
2004-09-01 9:50 f_ops flag to speed up compatible " filia
2004-09-01 9:52 ` Arjan van de Ven
2004-09-01 10:16 ` filia
[not found] ` <4135B9FC.7050602@hist.no>
2004-09-01 13:29 ` Ihar 'Philips' Filipau
2004-09-01 15:28 ` Ihar 'Philips' Filipau
2004-09-02 7:29 ` Helge Hafting
2004-09-01 13:43 ` Olivier Galibert
2004-09-01 15:36 Albert Cahalan
2004-09-01 15:59 ` Roland Dreier
2004-09-01 21:53 ` Michael S. Tsirkin
2004-09-01 22:58 ` Roland Dreier
2004-09-01 23:18 ` Michael S. Tsirkin
2004-09-01 15:40 Albert Cahalan
2004-09-01 21:23 ` Michael S. Tsirkin
2004-09-01 21:38 ` Lee Revell
2004-09-01 21:43 ` Chris Wright
2004-09-01 21:44 ` Roland Dreier
2004-12-27 22:22 Michael S. Tsirkin
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