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From: Riku Voipio <riku.voipio@iki.fi>
To: vibi sreenivasan <vibi_sreenivasan@cms.com>
Cc: Martin Mohring <martin.mohring@opensuse.org>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH 02/02] linux-user : add vmsplice system call
Date: Mon, 25 May 2009 17:04:54 +0300	[thread overview]
Message-ID: <20090525140454.GA6014@kos.to> (raw)
In-Reply-To: <1243231987.2177.7.camel@system>

On Mon, May 25, 2009 at 11:43:07AM +0530, vibi sreenivasan wrote:
> hi,
> 	Thanks for your comment.
> > fine that you provide missing syscalls for user mode one after the other.
> > 
> > I have one remark: if the host os kernel is too old to provide the
> > syscalls, they should be #if'ed out (tee, vmsplice & co).
> if the host kernel is too old , i think it will return -1 & set errno to
> ENOSYS.
> So isnt that same as putting #ifdef.

Yes, having old kernel is not a problem in this. However, having a
old libc when compiling qemu can be a problem. Think Redhat RHEL 4
or debian etch. vmsplice() is not available, and compiling qemu
would fail.

See how we #ifdef utimensat in linux-user/syscall.c and detect
availability in ./configure

Other than that, your patches looked ok.
 
> > Or even emulate the syscall - which can be quite hard.

> Hmm thinking on that. will it be worth?

This could be in interest for people who want to run qemu linux-user
on non-linux systems (such a *bsd). But that doesn't work yet,
and even when people get it working, new syscalls such as tee/splice
are not the most important ones to provide emulation for. Very
few applications use these syscalls yet.

      reply	other threads:[~2009-05-25 14:05 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-05-24  8:05 [Qemu-devel] [PATCH 02/02] linux-user : add vmsplice system call vibi sreenivasan
2009-05-24 18:21 ` Martin Mohring
2009-05-25  6:13   ` vibi sreenivasan
2009-05-25 14:04     ` Riku Voipio [this message]

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