From: Avi Kivity <avi@redhat.com>
To: Cam Macdonell <cam@cs.ualberta.ca>
Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org,
Anthony Liguori <anthony@codemonkey.ws>
Subject: Re: [PATCH v5 4/5] Inter-VM shared memory PCI device
Date: Mon, 10 May 2010 19:40:05 +0300 [thread overview]
Message-ID: <4BE836E5.9070106@redhat.com> (raw)
In-Reply-To: <AANLkTikWZ3hIsLFWEzbzbM0524EmMTt8YQfmxwpsku_h@mail.gmail.com>
On 05/10/2010 06:41 PM, Cam Macdonell wrote:
>
>> What would happen to any data written to the BAR before the the handshake
>> completed? I think it would disappear.
>>
> But, the BAR isn't there until the handshake is completed. Only after
> receiving the shared memory fd does my device call pci_register_bar()
> in the callback function. So there may be a case with BAR2 (the
> shared memory BAR) missing during initialization. FWIW, I haven't
> encountered this.
>
Well, that violates PCI. You can't have a PCI device with no BAR, then
have a BAR appear. It may work since the BAR is registered a lot faster
than the BIOS is able to peek at it, but it's a race nevertheless.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Cam Macdonell <cam@cs.ualberta.ca>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: [Qemu-devel] Re: [PATCH v5 4/5] Inter-VM shared memory PCI device
Date: Mon, 10 May 2010 19:40:05 +0300 [thread overview]
Message-ID: <4BE836E5.9070106@redhat.com> (raw)
In-Reply-To: <AANLkTikWZ3hIsLFWEzbzbM0524EmMTt8YQfmxwpsku_h@mail.gmail.com>
On 05/10/2010 06:41 PM, Cam Macdonell wrote:
>
>> What would happen to any data written to the BAR before the the handshake
>> completed? I think it would disappear.
>>
> But, the BAR isn't there until the handshake is completed. Only after
> receiving the shared memory fd does my device call pci_register_bar()
> in the callback function. So there may be a case with BAR2 (the
> shared memory BAR) missing during initialization. FWIW, I haven't
> encountered this.
>
Well, that violates PCI. You can't have a PCI device with no BAR, then
have a BAR appear. It may work since the BAR is registered a lot faster
than the BIOS is able to peek at it, but it's a race nevertheless.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2010-05-10 16:40 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-21 17:53 [PATCH v5 0/5] PCI Shared Memory device Cam Macdonell
2010-04-21 17:53 ` [Qemu-devel] " Cam Macdonell
2010-04-21 17:53 ` [PATCH v5 1/5] Device specification for shared memory PCI device Cam Macdonell
2010-04-21 17:53 ` [Qemu-devel] " Cam Macdonell
2010-04-21 17:53 ` [PATCH v5 2/5] Support adding a file to qemu's ram allocation Cam Macdonell
2010-04-21 17:53 ` [Qemu-devel] " Cam Macdonell
2010-04-21 17:53 ` [PATCH v5 3/5] Add functions for assigning ioeventfd and irqfds Cam Macdonell
2010-04-21 17:53 ` [Qemu-devel] " Cam Macdonell
2010-04-21 17:53 ` [PATCH v5 4/5] Inter-VM shared memory PCI device Cam Macdonell
2010-04-21 17:53 ` [Qemu-devel] " Cam Macdonell
2010-04-21 18:00 ` [PATCH v5 5/5] shared memory server for inter-VM shared memory Cam Macdonell
2010-04-21 18:00 ` [Qemu-devel] " Cam Macdonell
2010-05-05 16:57 ` [PATCH v5 4/5] RESEND: Inter-VM shared memory PCI device Cam Macdonell
2010-05-05 16:57 ` [Qemu-devel] " Cam Macdonell
2010-05-06 17:32 ` [PATCH v5 4/5] " Anthony Liguori
2010-05-06 17:32 ` [Qemu-devel] " Anthony Liguori
2010-05-06 17:59 ` Cam Macdonell
2010-05-06 17:59 ` [Qemu-devel] " Cam Macdonell
2010-05-10 11:59 ` Avi Kivity
2010-05-10 11:59 ` [Qemu-devel] " Avi Kivity
2010-05-10 15:22 ` Cam Macdonell
2010-05-10 15:22 ` [Qemu-devel] " Cam Macdonell
2010-05-10 15:28 ` Avi Kivity
2010-05-10 15:28 ` [Qemu-devel] " Avi Kivity
2010-05-10 15:38 ` Anthony Liguori
2010-05-10 15:38 ` [Qemu-devel] " Anthony Liguori
2010-05-10 16:20 ` Cam Macdonell
2010-05-10 16:20 ` [Qemu-devel] " Cam Macdonell
2010-05-10 16:52 ` Anthony Liguori
2010-05-10 16:52 ` [Qemu-devel] " Anthony Liguori
2010-05-18 16:58 ` Cam Macdonell
2010-05-18 16:58 ` [Qemu-devel] " Cam Macdonell
2010-05-18 17:27 ` Avi Kivity
2010-05-18 17:27 ` [Qemu-devel] " Avi Kivity
2010-05-10 16:59 ` Avi Kivity
2010-05-10 16:59 ` [Qemu-devel] " Avi Kivity
2010-05-10 17:25 ` Anthony Liguori
2010-05-10 17:25 ` [Qemu-devel] " Anthony Liguori
2010-05-10 17:43 ` Cam Macdonell
2010-05-10 17:43 ` [Qemu-devel] " Cam Macdonell
2010-05-10 17:52 ` Anthony Liguori
2010-05-10 17:52 ` [Qemu-devel] " Anthony Liguori
2010-05-10 18:01 ` Cam Macdonell
2010-05-10 18:01 ` [Qemu-devel] " Cam Macdonell
2010-05-11 7:59 ` Avi Kivity
2010-05-11 7:59 ` [Qemu-devel] " Avi Kivity
2010-05-11 13:10 ` Anthony Liguori
2010-05-11 13:10 ` [Qemu-devel] " Anthony Liguori
2010-05-11 14:03 ` Avi Kivity
2010-05-11 14:03 ` [Qemu-devel] " Avi Kivity
2010-05-11 14:17 ` Cam Macdonell
2010-05-11 14:17 ` [Qemu-devel] " Cam Macdonell
2010-05-11 14:53 ` Avi Kivity
2010-05-11 14:53 ` [Qemu-devel] " Avi Kivity
2010-05-11 15:51 ` Anthony Liguori
2010-05-11 15:51 ` [Qemu-devel] " Anthony Liguori
2010-05-11 16:39 ` Cam Macdonell
2010-05-11 16:39 ` [Qemu-devel] " Cam Macdonell
2010-05-11 17:05 ` Anthony Liguori
2010-05-11 17:05 ` [Qemu-devel] " Anthony Liguori
2010-05-11 17:50 ` Cam Macdonell
2010-05-11 17:50 ` [Qemu-devel] " Cam Macdonell
2010-05-11 18:13 ` Avi Kivity
2010-05-11 18:13 ` [Qemu-devel] " Avi Kivity
2010-05-12 15:32 ` Cam Macdonell
2010-05-12 15:32 ` [Qemu-devel] " Cam Macdonell
2010-05-12 15:48 ` Avi Kivity
2010-05-12 15:48 ` [Qemu-devel] " Avi Kivity
2010-05-11 18:09 ` Avi Kivity
2010-05-11 18:09 ` [Qemu-devel] " Avi Kivity
2010-05-11 7:55 ` Avi Kivity
2010-05-11 7:55 ` [Qemu-devel] " Avi Kivity
2010-05-10 15:41 ` Cam Macdonell
2010-05-10 15:41 ` [Qemu-devel] " Cam Macdonell
2010-05-10 16:40 ` Avi Kivity [this message]
2010-05-10 16:40 ` Avi Kivity
2010-05-10 16:48 ` Cam Macdonell
2010-05-10 16:48 ` [Qemu-devel] " Cam Macdonell
2010-05-12 15:49 ` Avi Kivity
2010-05-12 15:49 ` [Qemu-devel] " Avi Kivity
2010-05-12 16:14 ` Cam Macdonell
2010-05-12 16:14 ` [Qemu-devel] " Cam Macdonell
2010-05-12 16:45 ` Avi Kivity
2010-05-12 16:45 ` [Qemu-devel] " Avi Kivity
2010-05-10 23:17 ` Cam Macdonell
2010-05-10 23:17 ` [Qemu-devel] " Cam Macdonell
2010-05-11 8:03 ` Avi Kivity
2010-05-11 8:03 ` [Qemu-devel] " Avi Kivity
2010-05-13 21:10 ` Cam Macdonell
2010-05-13 21:10 ` [Qemu-devel] " Cam Macdonell
2010-05-15 6:05 ` Avi Kivity
2010-05-15 6:05 ` [Qemu-devel] " Avi Kivity
2010-05-10 10:43 ` [PATCH v5 3/5] Add functions for assigning ioeventfd and irqfds Avi Kivity
2010-05-10 10:43 ` [Qemu-devel] " Avi Kivity
2010-05-10 15:13 ` Cam Macdonell
2010-05-10 15:13 ` [Qemu-devel] " Cam Macdonell
2010-05-10 15:17 ` Avi Kivity
2010-05-10 15:17 ` [Qemu-devel] " Avi Kivity
2010-05-10 10:39 ` [PATCH v5 2/5] Support adding a file to qemu's ram allocation Avi Kivity
2010-05-10 10:39 ` [Qemu-devel] " Avi Kivity
2010-05-10 15:32 ` Cam Macdonell
2010-05-10 15:32 ` [Qemu-devel] " Cam Macdonell
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