Re: [PATCH corrected RFC] uio: add generic driver for PCI 2.3 devices

From: Anthony Liguori <anthony@codemonkey.ws>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: kvm@vger.kernel.org, avi@redhat.com
Subject: Re: [PATCH corrected RFC] uio: add generic driver for PCI 2.3 devices
Date: Thu, 09 Jul 2009 15:14:53 -0500	[thread overview]
Message-ID: <4A564FBD.3020905@codemonkey.ws> (raw)
In-Reply-To: <20090709181258.GA4340@redhat.com>

Michael S. Tsirkin wrote:
> On Thu, Jul 09, 2009 at 09:54:43AM -0500, Anthony Liguori wrote:
>   
>> I know it's not strictly needed for PCI pass through, but it would be  
>> useful to register the IO regions via UIO.  The userspace implementation  
>> would then use UIO strictly instead of poking the sysfs pci info  
>> directly.  I think that ends up being cleaner.
>>     
>
> Hmm, this is good for specific drivers, but for a generic one like qemu,
> still need sysfs to figure out the size at least,

size of what?

>  and
> we need config accesses which uio does not support now.
> And if you use libpci as qemu does now, this interface will likely
> go unused. So .. there does not seem to be much point at the moment.
>   

Right, I would expect uio to replace libpci.

> My idea is, let's start with a minimal interface, longer term
> let's see if we can add config access, mmap and other stuff like eventfd.
> Makes sense?
>   

It can certainly grow more features down the road.

Regards,

Anthony Liguori