Hi,
On May 11 2017 17:46, Takashi Iwai wrote:
On Thu, 11 May 2017 10:21:33 +0200, Christoph Hellwig wrote:
Ho Jaroslav, hi Takashi,
do you know who still uses the sound/oss drivers and why? I've recently been looking into getting rid of set_fs for using copy_{from,to}_user and friends on kernel pointers, and the sound code is a big abuser, both ALSA and the legacy OSS code.
Yeah, I also started looking at it after reading the LWN article. The removal of set_fs() in ALSA part was already finished, and I'm currently brushing up the patches. It'll be in 4.13 at latest.
Eventually, I'm also working for it[1]. I'm willing to review your changes, so please add me into CC list when you post patches.
Instead, In this development cycle, I'll post my patches for tracepoints for PCM parameter handling and misc refactoring[2]. (I've already done most of the work.)
But the set_fs() usage in OSS code is hard to get rid of, due to the in-kernel ioctl calls, and I really don't want to touch such dusty codes, either. So I wanted to post the very same question, but you were faster :)
But looking at the OSS code it's pretty grotty, and also appears to be pretty much unmaintained except for global cleanups. Is there any chance we could look into getting rid of it over the next few merge windows or are there people that rely on it?
I don't think there are any active users. The only slight concern is that there are a few ancient devices that are supported only by some OSS drivers. But these are over decades, and very unlikely alive.
That said, I'd love to drop that legacy stuff; or maybe as a soft-landing, begin with disabling the build of sound/oss in Kconfig.
The latter can be done even for 4.12, if Linus doesn't mind.
I think we don't need to care of drivers implemented with Open Sound System. In my understanding, stuffs in 'sound/core/oss/*' give Open Sound System compatibility layer for Open Sound System applications. In short, it gives a way for the applications to use drivers in ALSA by Open Sound System interfaces. Even if this layer is missing, the applications are still available with Open Sound System Proxy Daemon[3] with FUSE/CURE assistances. I believe we can get rid of them without any actual disadvantages.
[1] https://github.com/takaswie/sound/tree/topic/segment-in-pcm [2] https://github.com/takaswie/sound/tree/topic/trace+refactor [3] https://github.com/libfuse/osspd
Regards
Takashi Sakamoto