> On Wed, Jan 18, 2017 at 04:56:58AM +0000, Li, Liang Z wrote: > > > > - virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); > > > > - virtqueue_kick(vq); > > > > +static void do_set_resp_bitmap(struct virtio_balloon *vb, > > > > + unsigned long base_pfn, int pages) > > > > > > > > - /* When host has read buffer, this completes via balloon_ack */ > > > > - wait_event(vb->acked, virtqueue_get_buf(vq, &len)); > > > > +{ > > > > + __le64 *range = vb->resp_data + vb->resp_pos; > > > > > > > > + if (pages > (1 << VIRTIO_BALLOON_NR_PFN_BITS)) { > > > > + /* when the length field can't contain pages, set it to 0 to > > > > > > /* > > > * Multi-line > > > * comments > > > * should look like this. > > > */ > > > > > > Also, pls start sentences with an upper-case letter. > > > > > > > Sorry for that. > > > > > > + * indicate the actual length is in the next __le64; > > > > + */ > > > > > > This is part of the interface so should be documented as such. > > > > > > > + *range = cpu_to_le64((base_pfn << > > > > + VIRTIO_BALLOON_NR_PFN_BITS) | 0); > > > > + *(range + 1) = cpu_to_le64(pages); > > > > + vb->resp_pos += 2; > > > > > > Pls use structs for this kind of stuff. > > > > I am not sure if you mean to use > > > > struct range { > > __le64 pfn: 52; > > __le64 nr_page: 12 > > } > > Instead of the shift operation? > > Not just that. You want to add a pages field as well. > pages field? Could you give more hints? > Generally describe the format in the header in some way so host and guest > can easily stay in sync. 'VIRTIO_BALLOON_NR_PFN_BITS' is for this purpose and it will be passed to the related function in page_alloc.c as a parameter. Thanks! Liang > All the pointer math and void * means we get zero type safety and I'm not > happy about it. > > It's not good that virtio format seeps out to page_alloc anyway. > If unavoidable it is not a good idea to try to hide this fact, people will assume > they can change the format at will. > > -- > MST -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href