From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH v3 1/1] Shared memory uio_pci driver Date: Thu, 01 Apr 2010 11:58:29 +0300 Message-ID: <4BB46035.70701@redhat.com> References: <1269497376-21903-1-git-send-email-cam@cs.ualberta.ca> <4BAB30EE.4020509@redhat.com> <8286e4ee1003250924q7cca5e71u8b8b7c6d8b785eb8@mail.gmail.com> <4BAB90BB.5030401@redhat.com> <8286e4ee1003260914u5e6ceee2pf0c00590de182fb6@mail.gmail.com> <4BAE44F2.20801@redhat.com> <8286e4ee1003281248k204a5bd4tc48e6ccc755918b@mail.gmail.com> <4BB114AC.9040902@redhat.com> <20100331091250.GA31085@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Cam Macdonell , qemu-devel@nongnu.org, kvm@vger.kernel.org To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20100331091250.GA31085@redhat.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org Errors-To: qemu-devel-bounces+gceq-qemu-devel=gmane.org@nongnu.org List-Id: kvm.vger.kernel.org On 03/31/2010 12:12 PM, Michael S. Tsirkin wrote: > > >> $ echo 4> /sys/.../msix/allocate >> $ # subdirectories 0 1 2 3 magically appear >> $ # bind fd 13 to msix >> > There's no way to know, when qemu starts, how many vectors will be used > by driver. So I think we can just go ahead and allocate as many vectors > as supported by device at the moment when the first eventfd is bound. > That will cause a huge amount of vectors to be allocated. It's better to do this dynamically in response to guest programming. >> $ echo 13> /sys/.../msix/2/bind-fd >> > I think that this one can't work, both fd 13 and sysfs file will get > closed when /bin/echo process exits. > I meant figuratively. It's pointless to bind an eventfd from a shell. You'd use fprintf() from qemu to bind the eventfd. >> $ # from now on, msix interrupt 2 will call eventfd_signal() on fd 13 >> >> Call me old fashioned, but I prefer ioctls. >> > I think we will have to use ioctl or irqcontrol because of lifetime > issues outlines above. > The lifetime issues don't exist if you do all that from qemu. That's not to say I prefer sysfs to ioctl. What's irqcontrol? -- error compiling committee.c: too many arguments to function