From: Gerd Hoffmann <kraxel@redhat.com>
To: Gleb Natapov <gleb@redhat.com>
Cc: Peter Maydell <peter.maydell@linaro.org>,
Anthony Liguori <aliguori@us.ibm.com>,
kvm@vger.kernel.org, "Michael S. Tsirkin" <mst@redhat.com>,
virtualization@lists.linux-foundation.org,
Stefan Hajnoczi <stefanha@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Paolo Bonzini <pbonzini@redhat.com>,
KONRAD Frederic <fred.konrad@greensocs.com>
Subject: Re: [PATCH RFC] virtio-pci: new config layout: using memory BAR
Date: Thu, 06 Jun 2013 17:22:44 +0200 [thread overview]
Message-ID: <51B0A944.8030704@redhat.com> (raw)
In-Reply-To: <20130606151012.GD4725@redhat.com>
Hi,
>> For seabios itself this isn't a big issue, see pci_{readl,writel} in
>> src/pci.c. When called in 16bit mode it goes into 32bit mode
>> temporarily, just for accessing the mmio register. ahci driver uses it,
>> xhci driver (wip atm) will use that too, and virtio-{blk,scsi} drivers
>> in seabios can do the same.
>>
> Isn't this approach broken? How can SeaBIOS be sure it restores real
> mode registers to exactly same state they were before entering 32bit
> mode?
Don't know the details of that magic. Kevin had some concerns on the
stability of this, so maybe there is a theoretic hole. So far I havn't
seen any issues in practice, but also didn't stress it too much.
Basically only used that with all kinds of boot loaders, could very well
be it breaks if you try to use that with more esoteric stuff such as dos
extenders, then hit unhandled corner cases ...
cheers,
Gerd
next prev parent reply other threads:[~2013-06-06 15:22 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-28 16:03 [PATCH RFC] virtio-pci: new config layout: using memory BAR Michael S. Tsirkin
2013-05-28 17:15 ` Anthony Liguori
2013-05-28 17:15 ` Anthony Liguori
2013-05-28 17:32 ` Michael S. Tsirkin
2013-05-28 17:43 ` Paolo Bonzini
2013-05-29 2:02 ` Laszlo Ersek
2013-05-29 2:02 ` Laszlo Ersek
2013-05-29 4:33 ` Rusty Russell
2013-05-29 4:33 ` Rusty Russell
2013-05-29 7:27 ` Paolo Bonzini
2013-05-29 8:05 ` Michael S. Tsirkin
2013-05-29 10:07 ` Laszlo Ersek
2013-05-28 18:53 ` Anthony Liguori
2013-05-28 19:27 ` Michael S. Tsirkin
2013-05-29 4:31 ` Rusty Russell
2013-05-29 4:31 ` Rusty Russell
2013-05-29 8:24 ` Michael S. Tsirkin
2013-05-29 8:52 ` Paolo Bonzini
2013-05-29 9:00 ` Peter Maydell
2013-05-29 10:08 ` Michael S. Tsirkin
2013-05-29 10:53 ` Peter Maydell
2013-05-29 12:16 ` Michael S. Tsirkin
2013-05-29 12:28 ` Paolo Bonzini
2013-05-29 12:37 ` Michael S. Tsirkin
2013-05-29 12:52 ` Anthony Liguori
2013-05-29 12:52 ` Anthony Liguori
2013-05-29 13:24 ` Michael S. Tsirkin
2013-05-29 13:35 ` Peter Maydell
2013-05-29 13:35 ` Peter Maydell
2013-05-29 13:41 ` Paolo Bonzini
2013-05-29 14:02 ` Michael S. Tsirkin
2013-05-29 14:18 ` Anthony Liguori
2013-05-29 14:18 ` Anthony Liguori
2013-05-30 7:43 ` Michael S. Tsirkin
2013-05-29 14:16 ` Anthony Liguori
2013-05-29 14:16 ` Anthony Liguori
2013-05-29 14:30 ` Michael S. Tsirkin
2013-05-29 14:32 ` Paolo Bonzini
2013-05-29 14:52 ` Michael S. Tsirkin
2013-05-29 14:55 ` Anthony Liguori
2013-05-29 16:12 ` Michael S. Tsirkin
2013-05-29 18:16 ` Michael S. Tsirkin
2013-05-29 14:55 ` Anthony Liguori
2013-05-30 3:58 ` Rusty Russell
2013-05-30 3:58 ` Rusty Russell
2013-05-30 5:55 ` Michael S. Tsirkin
2013-05-30 7:55 ` Michael S. Tsirkin
2013-06-03 0:17 ` Rusty Russell
2013-05-30 13:53 ` Anthony Liguori
2013-05-30 13:53 ` Anthony Liguori
2013-05-30 14:01 ` Michael S. Tsirkin
2013-06-03 0:26 ` Rusty Russell
2013-06-03 10:11 ` Michael S. Tsirkin
2013-06-04 5:31 ` Rusty Russell
2013-06-04 6:42 ` Michael S. Tsirkin
2013-06-05 7:19 ` Rusty Russell
2013-06-05 10:22 ` Michael S. Tsirkin
2013-06-05 12:59 ` Anthony Liguori
2013-06-05 14:09 ` Michael S. Tsirkin
2013-06-05 15:08 ` Anthony Liguori
2013-06-05 15:19 ` Michael S. Tsirkin
2013-06-05 15:46 ` Anthony Liguori
2013-06-05 15:46 ` Anthony Liguori
2013-06-05 16:20 ` Michael S. Tsirkin
2013-06-05 18:57 ` Anthony Liguori
2013-06-05 19:43 ` Michael S. Tsirkin
2013-06-05 19:52 ` Michael S. Tsirkin
2013-06-05 20:45 ` Anthony Liguori
2013-06-05 21:15 ` H. Peter Anvin
2013-06-05 21:15 ` Michael S. Tsirkin
2013-06-05 20:42 ` Anthony Liguori
2013-06-05 21:14 ` Michael S. Tsirkin
2013-06-05 21:53 ` Anthony Liguori
2013-06-05 21:53 ` Anthony Liguori
2013-06-05 22:19 ` Benjamin Herrenschmidt
2013-06-05 22:53 ` Anthony Liguori
2013-06-05 23:27 ` Benjamin Herrenschmidt
2013-06-05 19:54 ` Michael S. Tsirkin
2013-06-06 3:42 ` Rusty Russell
2013-06-06 14:59 ` Anthony Liguori
2013-06-07 1:58 ` Rusty Russell
2013-06-07 8:25 ` Peter Maydell
2013-06-05 21:10 ` H. Peter Anvin
2013-06-05 21:17 ` Michael S. Tsirkin
2013-06-05 21:50 ` Anthony Liguori
2013-06-05 21:55 ` H. Peter Anvin
2013-06-05 22:08 ` Anthony Liguori
2013-06-05 23:07 ` H. Peter Anvin
2013-06-06 0:41 ` Anthony Liguori
2013-06-06 6:34 ` Gleb Natapov
2013-06-06 13:53 ` H. Peter Anvin
2013-06-06 15:02 ` Anthony Liguori
2013-06-07 11:30 ` Gleb Natapov
2013-06-11 7:10 ` Michael S. Tsirkin
2013-06-11 7:53 ` Gleb Natapov
2013-06-11 8:02 ` Michael S. Tsirkin
2013-06-11 8:03 ` Gleb Natapov
2013-06-11 8:19 ` Michael S. Tsirkin
2013-06-11 8:22 ` Gleb Natapov
2013-06-11 8:30 ` Michael S. Tsirkin
2013-06-11 8:32 ` Gleb Natapov
2013-06-11 8:04 ` Michael S. Tsirkin
2013-06-06 15:02 ` Anthony Liguori
2013-06-06 15:06 ` Gerd Hoffmann
2013-06-06 15:10 ` Gleb Natapov
2013-06-06 15:19 ` H. Peter Anvin
2013-06-06 15:22 ` Gerd Hoffmann [this message]
2013-07-08 4:25 ` Kevin O'Connor
2013-06-06 8:02 ` Michael S. Tsirkin
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