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Date: Sun, 1 Apr 2007 10:31:29 -0700 (PDT)
From: Davide Libenzi <davidel@xmailserver.org>
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To: Linus Torvalds <torvalds@linux-foundation.org>
cc: Avi Kivity <avi@argo.co.il>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>, Ingo Molnar <mingo@elte.hu>,
       Suparna Bhattacharya <suparna@in.ibm.com>,
       Zach Brown <zach.brown@oracle.com>, Benjamin LaHaise <bcrl@kvack.org>
Subject: Re: [patch 13/13] signal/timer/event fds v9 - KAIO eventfd support
 example ...
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On Sun, 1 Apr 2007, Linus Torvalds wrote:

> On Sun, 1 Apr 2007, Davide Libenzi wrote:
> > 
> > > [also, minor nit: sys_eventfd() can legitimately return 0, but you're banning
> > > its use in aio.  userspace could easily dup() and close(), but...]
> > 
> > Noone said that binary compatibility comes free ;)
> > I'm truly open to other ways of integration, but I thought that binary 
> > compatibility is the key here.
> 
> I would suggest taking "aio_reserved3" and turning it into
> 
> 	__u32 aio_flags;
> 	__u32 aio_resfd;
> 
> if so. And then some bit in the "flags" field has to be set (say, 
> "IOCB_FLAG_RESFB") to enable this codepath, instead of expecting that 
> aio_resfd == 0 is special.
> 
> It's generally always a good thing to have a "flags" field anyway, exactly 
> because it allows for future expansion. 

Makes sense. I was actually thinking of using the higher bit to signal 
that, but a flags field makes more sense.



- Davide