search for: desc_next

...My bad, I will need to work on it. Here is an example: Let's assume device promised to consume packets in order ring size = 2 Ring is 0 initialized. Device initially polls DESC[0].flags for WRAP bit to change. driver adds: DESC[0].addr = 1234 DESC[0].id = 0 DESC[0].flags = DESC_DRIVER | DESC_NEXT | DESC_WRAP and DESC[0].addr = 5678 DESC[1].id = 1 DESC[1].flags = DESC_DRIVER | DESC_WRAP it now starts polling DESC[0] flags. Device reads 1234, executes it, does not use it. Device reads 5678, executes it, and uses it: DESC[0].id = 1 DESC[0].flags = 0 Device now polls DESC[0].flags for...

...t's assume device promised to consume packets in order > > ring size = 2 > > Ring is 0 initialized. > > Device initially polls DESC[0].flags for WRAP bit to change. > > driver adds: > > DESC[0].addr = 1234 > DESC[0].id = 0 > DESC[0].flags = DESC_DRIVER | DESC_NEXT | DESC_WRAP > > and > > DESC[0].addr = 5678 > DESC[1].id = 1 > DESC[1].flags = DESC_DRIVER | DESC_WRAP > > > it now starts polling DESC[0] flags. > > > Device reads 1234, executes it, does not use it. > > Device reads 5678, executes it, and uses it:...

...t's assume device promised to consume packets in order > > ring size = 2 > > Ring is 0 initialized. > > Device initially polls DESC[0].flags for WRAP bit to change. > > driver adds: > > DESC[0].addr = 1234 > DESC[0].id = 0 > DESC[0].flags = DESC_DRIVER | DESC_NEXT | DESC_WRAP > > and > > DESC[0].addr = 5678 > DESC[1].id = 1 > DESC[1].flags = DESC_DRIVER | DESC_WRAP > > > it now starts polling DESC[0] flags. > > > Device reads 1234, executes it, does not use it. > > Device reads 5678, executes it, and uses it:...

Michael, Would you please give an example or two how these two flags DESC_DRIVER and DESC_WRAP are used together? Like others, I am confused by the description and still don?t quite grok it. Steven On 9/25/17, 3:24 PM, "virtio-dev at lists.oasis-open.org on behalf of Michael S. Tsirkin" <virtio-dev at lists.oasis-open.org on behalf of mst at redhat.com> wrote: On Wed, Sep

...gt; > > > ring size = 2 > > > > Ring is 0 initialized. > > > > Device initially polls DESC[0].flags for WRAP bit to change. > > > > driver adds: > > > > DESC[0].addr = 1234 > > DESC[0].id = 0 > > DESC[0].flags = DESC_DRIVER | DESC_NEXT | DESC_WRAP > > > > and > > > > DESC[0].addr = 5678 > > DESC[1].id = 1 > > DESC[1].flags = DESC_DRIVER | DESC_WRAP > > > > > > it now starts polling DESC[0] flags. > > > > > > Device reads 1234, executes it, does not use...

On Wed, Sep 20, 2017 at 09:11:57AM +0000, Liang, Cunming wrote: > Hi Michael, > > > -----Original Message----- > > From: virtio-dev at lists.oasis-open.org [mailto:virtio-dev at lists.oasis-open.org] > > On Behalf Of Michael S. Tsirkin > > Sent: Sunday, September 10, 2017 1:06 PM > > To: virtio-dev at lists.oasis-open.org > > Cc: virtualization at

On Wed, Sep 20, 2017 at 09:11:57AM +0000, Liang, Cunming wrote: > Hi Michael, > > > -----Original Message----- > > From: virtio-dev at lists.oasis-open.org [mailto:virtio-dev at lists.oasis-open.org] > > On Behalf Of Michael S. Tsirkin > > Sent: Sunday, September 10, 2017 1:06 PM > > To: virtio-dev at lists.oasis-open.org > > Cc: virtualization at

...o chain s/g entries in a request, same as virtio 1.0: /* This marks a buffer as continuing via the next field. */ #define VRING_DESC_F_NEXT 1 Unlike virtio 1.0, all descriptors must have distinct ID values. Also unlike virtio 1.0, use of this flag will be an optional feature (e.g. VIRTIO_F_DESC_NEXT) so both devices and drivers can opt out of it. * Indirect buffers Can be marked like in virtio 1.0: /* This means the buffer contains a table of buffer descriptors. */ #define VRING_DESC_F_INDIRECT 4 Unlike virtio 1.0, this is a table, not a list: struct indirect_descriptor_table { /...

...o chain s/g entries in a request, same as virtio 1.0: /* This marks a buffer as continuing via the next field. */ #define VRING_DESC_F_NEXT 1 Unlike virtio 1.0, all descriptors must have distinct ID values. Also unlike virtio 1.0, use of this flag will be an optional feature (e.g. VIRTIO_F_DESC_NEXT) so both devices and drivers can opt out of it. * Indirect buffers Can be marked like in virtio 1.0: /* This means the buffer contains a table of buffer descriptors. */ #define VRING_DESC_F_INDIRECT 4 Unlike virtio 1.0, this is a table, not a list: struct indirect_descriptor_table { /...