On Wed, 13 Nov 2019 15:32:44 +0100, Arnd Bergmann wrote: > > On Tue, Nov 12, 2019 at 9:37 PM Takashi Iwai <tiwai@xxxxxxx> wrote: > > On Tue, 12 Nov 2019 16:16:34 +0100, Arnd Bergmann wrote: > > > I would like to propose merging this into the alsa tree after > > > the v5.5 merge window for inclusion into v5.6, to allow a good > > > amount of testing, in particular for the header changes that > > > may cause problems for user space applications. > > > > Agreed, it's still no urgent problem. > > I actually do think it's getting urgent, anything that touches > the ABI must be done carefully and not rushed. > > The urgency at the moment is that developers are starting to > deploy systems with 64-bit time_t with musl-libc making this > the default now, and 32-bit risc-v not offering 32-bit time_t at all. > > At the moment, this means that audio support is broken for > them, and that needs to be fixed. > > The other reason why lots of people care about moving all user > space to 64-bit time_t is that 32-bit hardware is slowly starting > to become less common. We know there will still be many > 32-bit ARM systems operational in 2038, but most of them will > be on (then) 10+ year old hardware, running even older software > that already being worked on today. The longer it takes us to > stop using 32-bit time_t in user space, the more systems will > end up having to be thrown away rather than fixed. Don't worry, I planned merging the whole changes for 5.6. > > So now taking a quick look through the series, I find this approach is > > the way to go. Although one might get a bit more optimization after > > squeeze, it's already a good compromise between the readability and > > the efficiency. > > Thanks! > > > A slight uncertain implementation is the timer tread stuff, especially > > the conditional definition of SNDRV_TIMER_IOCTL_TREAD (IIRC, I already > > complained it in the past, too). But I have no other idea as well, so > > unless someone else gives a better option, we can live with that. > > We had discussed alternatives for this one last time, and decided > to go with the solution I posted here. The main alternative would > be to change the 'timespec' in snd_timer_tread to a fixed-length > structure based on two 'long' members. This would avoid the > need to match the command with the time_t type, but the cost would > be requiring CLOCK_MONOTONIC timestamps to avoid the > overflow, and changing all application source code that requires > the type to be compatible with 'timespec'. Fair enough. One thing I forgot to mention: when we add/modify the ioctl or ABI, we need to increment the protocol version, e.g. SNDRV_PCM_VERSION to indicate user-space the supported ABI. Please change these in your next patches, too. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx https://mailman.alsa-project.org/mailman/listinfo/alsa-devel
