On Mon, Apr 25, 2022 at 06:05:56PM +0100, Mark Cave-Ayland wrote:
On 25/04/2022 09:21, Martin Kletzander wrote:I wanted to deal with https://bugzilla.redhat.com/2043498 and I got a suggesstion that removing deprecated features could actually make it easier to propagate the error. In the end (last patch) it turns out the error is still just reported with error_fatal, so it probably is not really needed, but I really wanted to dig into QEMU more and learn some of the internals for quite some time now. So I used the opportunity. The one-liner ended up being an 18 patch series which was, for someone who has just one commit in QEMU codebase, a pretty challenging task. Although I tried my best to do things properly, I am not sure whether I handled everything correctly, hence the RFC. Any comments are very much appreciated. Thanks and have a nice day ;) Martin Kletzander (18): hw/audio: Remove -soundhw support hw/input/tsc210x: Extract common init code into new function hw/audio: Simplify hda audio init hw/audio/lm4549: Add errp error reporting to init function tests/qtest: Specify audiodev= and -audiodev ui/vnc: Require audiodev= Introduce machine's default-audiodev property audio: Add easy dummy audio initialiser hw/display/xlnx_dp.c: Add audiodev property hw/input/tsc210x.c: Support machine-default audiodev with fallback hw/arm: Support machine-default audiodev with fallback hw/ppc: Support machine-default audiodev with fallback audio: Make AUD_register_card fallible and require audiodev= audio: Require AudioState in AUD_add_capture audio: Be more strict during audio backend initialisation audio: Remove legacy audio environment variables and options audio: Remove unused can_be_default audio/spiceaudio: Fail initialisation when not using spice
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Thanks for the tidy-up! I'm not too familiar with the audio code, however one thing I noticed is that in patch 11 you are using qdev_prop_set_string() to set the audiodev for the machines. For CharDevs there already exists a qdev_prop_set_chr() function which is used to assign the chardev backend to the device, so I'm wondering if it makes sense to add a similar qdev_prop_set_audiodev() function in the same way? Then if the method of referencing the audiodev from the device ever changes from being a string containing the name, it won't require updating all of the callers.
I guess that could be possible, but I'm not familiar with QEMU code much and to be honest have no idea how I would go about doing that right now.
Finally a quick glance at the tsc210x and lm4549 devices indicates that they are using global device _init() functions which shouldn't really be used in modern implementations. If you are interested in QOMify-ing these devices as part of this work, then I can certainly help provide some pointers for getting started.
I thought about it for some devices. Not all the devices I touched here, because I feel like that would lead to a rabbit hole. And 18 patches just because I wanted to error out in one condition was already too much =) But I'll be glad for any pointers on where to start and how should I get to it. Thanks.
ATB, Mark.
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