Re: [Qemu-devel] [PATCH v1 1/2] vhost-user: support SET_MEM_TABLE waite the result of mmap

[Linhaifeng <haifeng.lin@huawei.com>]

On 2015/2/10 18:41, Michael S. Tsirkin wrote:
> On Tue, Feb 10, 2015 at 06:27:04PM +0800, Linhaifeng wrote:
>>
>>
>> On 2015/2/10 16:46, Michael S. Tsirkin wrote:
>>> On Tue, Feb 10, 2015 at 01:48:12PM +0800, linhaifeng wrote:
>>>> From: Linhaifeng <haifeng.lin@huawei.com>
>>>>
>>>> Slave should reply to master and set u64 to 0 if
>>>> mmap all regions success otherwise set u64 to 1.
>>>>
>>>> Signed-off-by: Linhaifeng <haifeng.lin@huawei.com>
>>>
>>> How does this work with existig slaves though?
>>>
>>
>> Slaves should work like this:
>>
>> int set_mem_table(...)
>> {
>>     ....
>>     for (idx = 0, i = 0; idx < memory.nregions; idx++) {
>> 	....
>>     	mem = mmap(..);
>> 	if (MAP_FAILED == mem) {
>> 		msg->msg.u64 = 1;
>>                 msg->msg.size = MEMB_SIZE(VhostUserMsg, u64);
>> 		return 1;
>> 	}
>>     }
>>
>>     ....
>>
>>     msg->msg.u64 = 0;
>>     msg->msg.size = MEMB_SIZE(VhostUserMsg, u64);
>>     return 1;
>> }
>>
>> If slaves not reply QEMU will always wait.
> 
> Are you sure existing slaves reply?

No.May be the existing slaves need add reply in their codes.

> 
>>>> ---
>>>>  docs/specs/vhost-user.txt | 1 +
>>>>  1 file changed, 1 insertion(+)
>>>>
>>>> diff --git a/docs/specs/vhost-user.txt b/docs/specs/vhost-user.txt
>>>> index 650bb18..c96bf6b 100644
>>>> --- a/docs/specs/vhost-user.txt
>>>> +++ b/docs/specs/vhost-user.txt
>>>> @@ -171,6 +171,7 @@ Message types
>>>>        Id: 5
>>>>        Equivalent ioctl: VHOST_SET_MEM_TABLE
>>>>        Master payload: memory regions description
>>>> +      Slave payload: u64 (0:success >0:failed)
>>>>  
>>>>        Sets the memory map regions on the slave so it can translate the vring
>>>>        addresses. In the ancillary data there is an array of file descriptors
>>>> -- 
>>>> 1.7.12.4
>>>>
>>>
>>>
>>
>> -- 
>> Regards,
>> Haifeng
> 
> .
> 

-- 
Regards,
Haifeng