Re: [Qemu-devel] [PATCH] qemu-ga: Fix linux build with trace backend

[Michael Roth <mdroth@linux.vnet.ibm.com>]

On 08/29/2011 02:20 PM, Stefan Weil wrote:
> Am 29.08.2011 20:32, schrieb Lluís:
>> Stefan Weil writes:
>>> Builds with configure --enable-trace-backend=simple failed on linux
>>> because qemu-ga then uses simpletrace.c which needs get_clock which
>>> needs use_rt_clock which was unresolved.
>>> Adding qemu-timer-common.o fixes this. It adds a little overhead
>>> (about 150 byte).
>>
>> There are a couple of threads associated to this very same topic:
>>
>> http://lists.gnu.org/archive/html/qemu-devel/2011-08/msg02915.html
>> http://lists.gnu.org/archive/html/qemu-devel/2011-08/msg03302.html
>>
>> Lluis
>
> Thanks for the links. So we now have three patch sets for one problem,
> and it will be fixed by a maintainer commit soon :-)
>

4, actually :) An alternative proposal from Blue was setting 
CONFIG_QEMU_TIMER based on whether or not qemu-timer-common.o was needed 
for a particular dependency, so anyone dependent on, say, trace-obj-y 
could just have:

blah-obj-$(CONFIG_QEMU_TIMER) += qemu-timer-common.o

I CC'd you on the patch.

> I personally prefer Blue Swirl's patch (which avoids the overhead)
> or my own patch (which adds a little overhead but is the simplest
> of all three patches). Sorting lists of object files and removing
> duplicates looks strange in my opinion (and might also be bad when
> related code no longer shares the same memory page).
>

I actually preferred the sorted list approach, I think it mirrors how 
most projects handle duplicate header includes and allows for defining a 
self-sufficient group of objects without needed to worry whether 2 
groups list the same object as a dependency. This allows results in one 
group being underspecified and any subsequent user of that group to be 
aware of what's missing.

> With my patch, qemu-ga and the other tools (qemu-io, qemu-img, ...)
> also use similar object lists.
>
> Kind regards,
> Stefan
>
>
>