lkml.org 
[lkml]   [2011]   [Nov]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: virtio-pci new configuration proposal
On Wed, Nov 02, 2011 at 08:49:27PM +0200, Sasha Levin wrote:
> This is a proposal for a new layout of the virtio-pci config space.
>
> We will separate the current configuration into two: A virtio-pci common
> configuration and a device specific configuration. This allows more flexibility
> with adding features and makes usage easier, specifically in cases like the
> ones in virtio-net where device specific configurations depend on device
> specific features.
>
> The preferred location of the configuration will be a MMIO BAR, therefore
> several size optimizations such as the queue selector which were useful
> on a PIO BAR were removed and linked lists were introduced to add
> flexibility to existing structures in attempt to keep their size and
> offsets constant and not dependent on features.
>
> While this is not a complete specification, it describes all the main
> structures and should be enough to make sure the idea is solid before
> going into implementation specifics.
>
> A new virtio-pci capability structure will be introduced. This structure
> will be used to describe the basics of a virtio-pci device. The
> structure is actually a PCI capability structure which wraps the new virtio-pci
> capability structure:
>
> +------------++------------+------------+------------+--------------+-----------------
> | Bits || 8 | 8 | 8 | 8 | Cap specific
> +------------++------------+------------+------------+--------------+-----------------
> | Read/Write || R | R | R | R | Cap specific
> +------------++------------+------------+------------+--------------+-----------------
> | Purpose || Capability | Capability | virtio-pci | virtio-pci | Cap specific
> | || ID | Next PTR | Cap ID | Next Cap PTR |
> +------------++------------+------------+------------+--------------+-----------------
>
> Currently, only one virtio-pci capability is defined, and is the one that defines
> the layout of the virtio-pci config space.
>
> VIRTIO_PCI_C_LAYOUT:
>
> +------------++---------------+---------------+-----------------+-----------------+
> | Bits || 29 | 3 | 29 | 3 |
> +------------++---------------+---------------+-----------------+-----------------+
> | Read/Write || R | R | R | R |
> +------------++---------------+---------------+-----------------+-----------------+
> | Purpose || Common config | Common config | Device specific | Device specific |
> | || Offset | BIR | Offset | BIR |
> +------------++---------------+---------------+-----------------+-----------------+

I'm implementing a different layout, with
separate capabilities for common and device specific
fields.


\
 
 \ /
  Last update: 2011-11-02 20:09    [W:0.070 / U:3.020 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site