[dpdk-dev] vhost-user technical isssues
Linhaifeng
haifeng.lin at huawei.com
Thu Nov 13 07:27:42 CET 2014
On 2014/11/12 5:37, Xie, Huawei wrote:
> Hi Tetsuya:
> There are two major technical issues in my mind for vhost-user implementation.
>
> 1) memory region map
> Vhost-user passes us file fd and offset for each memory region. Unfortunately the mmap offset is "very" wrong. I discovered this issue long time ago, and also found
> that I couldn't mmap the huge page file even with correct offset(need double check).
> Just now I find that people reported this issue on Nov 3.
> [Qemu-devel] [PULL 27/29] vhost-user: fix mmap offset calculation
> Anyway, I turned to the same idea used in our DPDK vhost-cuse: only use the fd for region(0) to map the whole file.
> I think we should use this way temporarily to support qemu-2.1 as it has that bug.
>
the size of region 0 is not same as the file size. may be you should mmap the other region.
region 0:
gpa = 0x0
size = 655360
ua = 0x2aaaaac00000
offset = 0
region 1:// use this region to mmap.BTW how to avoid mmap twice when there are two devices?
gpa = 0xC0000
size = 2146697216
ua = 0x2aaaaacc0000
offset = 786432
> 2) what message is the indicator for vhost start/release?
> Previously for vhost-cuse, it has SET_BACKEND message.
> What we should do for vhost-user?
> SET_VRING_KICK for start?
> What about for release?
> Unlike the kernel virtio, the DPDK virtio in guest could be restarted.
>
> Thoughts?
>
> -huawei
>
>
--
Regards,
Haifeng
More information about the dev
mailing list