From: Dor Laor <dor.laor-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
To: Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
Cc: kvm-devel-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
Jan Kiszka <jan.kiszka-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
Subject: Re: [PATCH] fix reading from character devices
Date: Mon, 21 Jan 2008 12:43:18 +0200 [thread overview]
Message-ID: <1200912198.3188.6.camel@localhost.localdomain> (raw)
In-Reply-To: <47947045.6040106-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
On Mon, 2008-01-21 at 12:13 +0200, Avi Kivity wrote:
> Jan Kiszka wrote:
> > Hi Avi,
> >
> > commit "kvm: qemu: consume all pending I/O in I/O loop"
> > (8ab8bb09f1115b9bf733f885cc92b6c63d83f420) broke reading data bursts
> > from serial devices (and maybe from other character devices as well) by
> > guests. Reason: serial devices do input flow control via fd_read_poll,
> > but qemu now ignores this fact by pushing all data into the virtual
> > device as soon as it is available.
> >
> > Patch below is not really nice (just as the whole internal virtual I/O
> > interface at the moment, IMHO), but it re-enables the serial ports for
> > now.
> >
> >
>
> I'm worried that it will break Dor's hack that speeds up virtio. Dor?
>
It should be fine. Tap device without my hack has fd_read_poll null and
I hacked it to have a handler that returns false if virtio is used and
true otherwise.
So Jan's patch should set 'more' to 1 and it will be like before.
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next prev parent reply other threads:[~2008-01-21 10:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-21 9:29 [PATCH] fix reading from character devices Jan Kiszka
[not found] ` <47946610.9040001-kv7WeFo6aLtBDgjK7y7TUQ@public.gmane.org>
2008-01-21 10:13 ` Avi Kivity
[not found] ` <47947045.6040106-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-21 10:43 ` Dor Laor [this message]
[not found] ` <1200912198.3188.6.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2008-01-21 10:50 ` Avi Kivity
[not found] ` <479478E6.6030903-atKUWr5tajBWk0Htik3J/w@public.gmane.org>
2008-01-21 11:23 ` Dor Laor
2008-02-21 12:32 ` Jan Kiszka
2008-02-22 7:41 ` Avi Kivity
2008-01-21 11:30 ` Jan Kiszka
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