[libvirt] [PATCH 2/2] V2 Modify generic ethernet interface so it will work when sVirt is enabled with qemu

[Eric Blake]

On 10/28/2011 08:59 PM, Tyler Coumbes wrote:
> On Thu, Oct 27, 2011 at 10:25 PM, Eric Blake<eblake at redhat.com>  wrote:
>> On 10/24/2011 05:44 PM, Tyler Coumbes wrote:
>>>
>>> This patch makes the changes to the generic ethernet interface for
>>> QEMU. Allowing it to be used with sVirt enabled.
>>>
>>>   src/qemu/qemu_command.c |   79
>>> ++++++++++++++++++++++++++++++++++++++++++++--
>>>   src/qemu/qemu_command.h |    4 ++
>>>   src/qemu/qemu_hotplug.c |   15 +++++++++
>>>   src/qemu/qemu_process.c |   13 ++++++++
>>>   4 files changed, 107 insertions(+), 4 deletions(-)
>>
>> I haven't reviewed this one closely yet, but it would help if you added a
>> test in tests/qemuxml2argvtest.c and a new pair of files in
>> tests/qemuxml2argvdata/* that exercise the code to prove the new command
>> line options look sane.
>>
>
> Two questions about creating a test for this code. How do I get the
> actual args so I can compare them to my expected args to see what
> isn't matching up? VIR_TEST_DEBUG=2 shows me what tests fail but not
> any detail about why.

VIR_TEST_DEBUG=1 shows a diff between expected and actual text; I'm not 
sure why VIR_TEST_DEBUG=2 wouldn't do the same, without diving into the 
test code more.

> I think it is because one of the parameters to
> qemu is a file descriptor which could change for each run. Is there
> some type of wildcard I can use like fd=%. I don't see any other tests
> using file descriptors to compare to and am not finding anything in
> any documentation I can find.

tests/qemuxml2argvdata/qemuxml2argv-restore-v2-fd.args is an example 
file that hard-codes a particular fd, and sets things up so that 
qemuxml2argvtest.c passes that hard-coded fd through DO_TEST_FULL, which 
in turn passes it through the migrateFd argument of qemuBuildCommandLine.

This may mean that we need to refactor things slightly to make it easier 
for testing.  One idea is to have normal calls to qemuBuildCommandLine 
call through a function pointer that opens a TAP and returns that FD; 
whereas running it from the testsuite sets that function pointer to 
provide a replacement function that just returns a hard-coded number 
rather than opening an fd.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org