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From: rusty@rustcorp.com.au (Rusty Russell)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3] virtio: Add platform bus driver for memory mapped virtio device
Date: Wed, 19 Oct 2011 13:27:20 +1030	[thread overview]
Message-ID: <87ty75adtb.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1318931075.3146.285.camel@hornet.cambridge.arm.com>

On Tue, 18 Oct 2011 10:44:35 +0100, Pawel Moll <pawel.moll@arm.com> wrote:
> > or actually specify it as
> > the power of 2 to use, (ie. valid values are 1 through 16, with 12 being
> > the value that virtio PCI would use).
> > 
> > Otherwise you have to do a divide on the qemu side.
> 
> Oh, really? My host-side implementation is just doing that:
> 
>         addr += align - 1;
>         addr &= ~(align - 1);

OK, so you're assuming power of 2.  Make sure you kill the guest or at
least the device if it's not though.

> \item The dynamic configuration changes, as described in p. 2.4.3
> ``Dealing With Configuration Changes'' are not permitted.

This means some devices simply won't work, at least in theory.  Why
don't you support this?

Thanks!
Rusty.

WARNING: multiple messages have this Message-ID (diff)
From: Rusty Russell <rusty@rustcorp.com.au>
To: Pawel Moll <pawel.moll@arm.com>
Cc: "linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel\@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"virtualization\@lists.linux-foundation.org" 
	<virtualization@lists.linux-foundation.org>,
	Anthony Liguori <aliguori@us.ibm.com>,
	"Michael S.Tsirkin" <mst@redhat.com>
Subject: Re: [PATCH v3] virtio: Add platform bus driver for memory mapped virtio device
Date: Wed, 19 Oct 2011 13:27:20 +1030	[thread overview]
Message-ID: <87ty75adtb.fsf@rustcorp.com.au> (raw)
In-Reply-To: <1318931075.3146.285.camel@hornet.cambridge.arm.com>

On Tue, 18 Oct 2011 10:44:35 +0100, Pawel Moll <pawel.moll@arm.com> wrote:
> > or actually specify it as
> > the power of 2 to use, (ie. valid values are 1 through 16, with 12 being
> > the value that virtio PCI would use).
> > 
> > Otherwise you have to do a divide on the qemu side.
> 
> Oh, really? My host-side implementation is just doing that:
> 
>         addr += align - 1;
>         addr &= ~(align - 1);

OK, so you're assuming power of 2.  Make sure you kill the guest or at
least the device if it's not though.

> \item The dynamic configuration changes, as described in p. 2.4.3
> ``Dealing With Configuration Changes'' are not permitted.

This means some devices simply won't work, at least in theory.  Why
don't you support this?

Thanks!
Rusty.

  reply	other threads:[~2011-10-19  2:57 UTC|newest]

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-09-28 13:47 [PATCH] virtio: Add platform bus driver for memory mapped virtio device Pawel Moll
2011-09-28 13:47 ` Pawel Moll
2011-09-28 13:54 ` Pawel Moll
2011-09-28 13:54   ` Pawel Moll
2011-10-03 23:46 ` Rusty Russell
2011-10-03 23:46   ` Rusty Russell
2011-10-04 16:16   ` Pawel Moll
2011-10-04 16:16     ` Pawel Moll
2011-10-05  1:10     ` Rusty Russell
2011-10-05  1:10       ` Rusty Russell
2011-10-05 10:06       ` Pawel Moll
2011-10-05 10:06         ` Pawel Moll
2011-10-05 18:57         ` [PATCH v2] " Pawel Moll
2011-10-05 18:57           ` Pawel Moll
2011-10-06 16:50           ` [PATCH v3] " Pawel Moll
2011-10-06 16:50             ` Pawel Moll
2011-10-06 17:13             ` Pawel Moll
2011-10-06 17:13               ` Pawel Moll
2011-10-18  4:09               ` Rusty Russell
2011-10-18  4:09                 ` Rusty Russell
2011-10-18  9:44                 ` Pawel Moll
2011-10-18  9:44                   ` Pawel Moll
2011-10-19  2:57                   ` Rusty Russell [this message]
2011-10-19  2:57                     ` Rusty Russell
2011-10-21 17:57                     ` Pawel Moll
2011-10-21 17:57                       ` Pawel Moll
2011-10-24  2:33                       ` Rusty Russell
2011-10-24  2:33                         ` Rusty Russell
2011-10-24 13:06                         ` Pawel Moll
2011-10-24 13:06                           ` Pawel Moll
2011-10-24 13:07                           ` [PATCH v4] " Pawel Moll
2011-10-24 13:07                           ` Pawel Moll
2011-10-24 13:07                             ` Pawel Moll
2011-10-25  1:13                             ` Rusty Russell
2011-10-25  1:13                               ` Rusty Russell
2011-10-26  4:06                           ` [PATCH v3] " Rusty Russell
2011-10-26  4:06                             ` Rusty Russell
2011-10-26  9:54                             ` Pawel Moll
2011-10-26 11:50                               ` Rusty Russell
2011-10-26 11:50                                 ` Rusty Russell
2011-10-24 13:06                         ` Pawel Moll
2011-10-13 16:49             ` Pawel Moll
2011-10-13 16:49               ` Pawel Moll
2011-10-05 10:39       ` [PATCH] " Michael S. Tsirkin
2011-10-05 10:39         ` Michael S. Tsirkin

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