search for: tail_id

...q, hdr, 0); >> + *prev_id = *head_id; >> + } >> + >> + virtqueue_add_chain_desc(vb->cmd_vq, addr, len, head_id, prev_id, 0); >> + if (*head_id == *prev_id) { > That's an ugly way to detect ring full. It's actually not detecting ring full. I will call it tail_id, instead of prev_id. So, *head_id == *tail_id is the case that the first desc was just added by virtqueue_add_chain_desc(). Best, Wei

...t; immediately > > Probably it wasn't clear. Please let me explain the two functions here: > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > grabs a desc from the vq and inserts it to the chain tail (which is indexed > by > prev_id, probably better to call it tail_id). Then, the new added desc > becomes > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > when it's > added to the chain, and set when another desc comes to follow later. And this only works if there are multiple rings like avail + descriptor ring. It won...

...t; immediately > > Probably it wasn't clear. Please let me explain the two functions here: > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > grabs a desc from the vq and inserts it to the chain tail (which is indexed > by > prev_id, probably better to call it tail_id). Then, the new added desc > becomes > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > when it's > added to the chain, and set when another desc comes to follow later. And this only works if there are multiple rings like avail + descriptor ring. It won...

On Wed, Jul 12, 2017 at 08:40:21PM +0800, Wei Wang wrote: > Add a new vq, cmdq, to handle requests between the device and driver. > > This patch implements two commands sent from the device and handled in > the driver. > 1) VIRTIO_BALLOON_CMDQ_REPORT_STATS: this command is used to report > the guest memory statistics to the host. The stats_vq mechanism is not > used when the

On Wed, Jul 12, 2017 at 08:40:21PM +0800, Wei Wang wrote: > Add a new vq, cmdq, to handle requests between the device and driver. > > This patch implements two commands sent from the device and handled in > the driver. > 1) VIRTIO_BALLOON_CMDQ_REPORT_STATS: this command is used to report > the guest memory statistics to the host. The stats_vq mechanism is not > used when the

...t clear. Please let me explain the two functions here: > > > > > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > > > grabs a desc from the vq and inserts it to the chain tail (which is indexed > > > by > > > prev_id, probably better to call it tail_id). Then, the new added desc > > > becomes > > > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > > > when it's > > > added to the chain, and set when another desc comes to follow later. > > And this only works if there are multi...

...t clear. Please let me explain the two functions here: > > > > > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > > > grabs a desc from the vq and inserts it to the chain tail (which is indexed > > > by > > > prev_id, probably better to call it tail_id). Then, the new added desc > > > becomes > > > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > > > when it's > > > added to the chain, and set when another desc comes to follow later. > > And this only works if there are multi...

On Wed, Jul 12, 2017 at 09:29:00PM +0800, Wei Wang wrote: > On 07/12/2017 09:06 PM, Michael S. Tsirkin wrote: > > On Wed, Jul 12, 2017 at 08:40:18PM +0800, Wei Wang wrote: > > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > > > index 28b0e96..9f27101 100644 > > > --- a/include/linux/virtio.h > > > +++ b/include/linux/virtio.h > >

On Wed, Jul 12, 2017 at 09:29:00PM +0800, Wei Wang wrote: > On 07/12/2017 09:06 PM, Michael S. Tsirkin wrote: > > On Wed, Jul 12, 2017 at 08:40:18PM +0800, Wei Wang wrote: > > > diff --git a/include/linux/virtio.h b/include/linux/virtio.h > > > index 28b0e96..9f27101 100644 > > > --- a/include/linux/virtio.h > > > +++ b/include/linux/virtio.h > >

...which always expose descriptors > immediately Probably it wasn't clear. Please let me explain the two functions here: 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): grabs a desc from the vq and inserts it to the chain tail (which is indexed by prev_id, probably better to call it tail_id). Then, the new added desc becomes the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc when it's added to the chain, and set when another desc comes to follow later. 2) virtqueue_add_chain(vq, head_id,..): expose the chain to the other end. So, if people want to add a d...

...>> Probably it wasn't clear. Please let me explain the two functions here: >> >> 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): >> grabs a desc from the vq and inserts it to the chain tail (which is indexed >> by >> prev_id, probably better to call it tail_id). Then, the new added desc >> becomes >> the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc >> when it's >> added to the chain, and set when another desc comes to follow later. > And this only works if there are multiple rings like > avail + d...

...ere: > > > > > > > > > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > > > > > grabs a desc from the vq and inserts it to the chain tail (which is indexed > > > > > by > > > > > prev_id, probably better to call it tail_id). Then, the new added desc > > > > > becomes > > > > > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > > > > > when it's > > > > > added to the chain, and set when another desc comes to follow later. > &gt...

...ere: > > > > > > > > > > 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): > > > > > grabs a desc from the vq and inserts it to the chain tail (which is indexed > > > > > by > > > > > prev_id, probably better to call it tail_id). Then, the new added desc > > > > > becomes > > > > > the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc > > > > > when it's > > > > > added to the chain, and set when another desc comes to follow later. > &gt...

...Please let me explain the two functions here: >>>> >>>> 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): >>>> grabs a desc from the vq and inserts it to the chain tail (which is indexed >>>> by >>>> prev_id, probably better to call it tail_id). Then, the new added desc >>>> becomes >>>> the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc >>>> when it's >>>> added to the chain, and set when another desc comes to follow later. >>> And this only works if ther...

...here: >>>>>> >>>>>> 1) virtqueue_add_chain_desc(vq, head_id, prev_id,..): >>>>>> grabs a desc from the vq and inserts it to the chain tail (which is indexed >>>>>> by >>>>>> prev_id, probably better to call it tail_id). Then, the new added desc >>>>>> becomes >>>>>> the tail (i.e. the last desc). The _F_NEXT flag is cleared for each desc >>>>>> when it's >>>>>> added to the chain, and set when another desc comes to follow later. >>...