Quoting Sean Paul (2020-01-15 13:41:58) > On Wed, Jan 15, 2020 at 10:36:36AM +0000, Chris Wilson wrote: > > Quoting Sean Paul (2020-01-14 17:21:43) > > > From: Sean Paul <seanpaul@xxxxxxxxxxxx> > > > > > > This patch uses a ring_buffer to keep a "flight recorder" (name credit Weston) > > > of DRM logs for a specified set of debug categories. The user writes a > > > bitmask of debug categories to the "trace_mask" node and can read log > > > messages from the "trace" node. > > > > > > These nodes currently exist in debugfs under the dri directory. I > > > intended on exposing all of this through tracefs originally, but the > > > tracefs entry points are not exposed, so there's no way to create > > > tracefs files from drivers at the moment. I think it would be a > > > worthwhile endeavour, but one requiring more time and conversation to > > > ensure the drm traces fit somewhere sensible. > > > > Fwiw, I have a need for client orientated debug message store, with > > the primary purpose of figuring out -EINVAL. We need per-client so we can > > put sensitive information about the potentially buggy client behaviour, > > and of course it needs to be accessible by the non-privileged client. > > > > On the execution side, it's easy to keep track of the client so we could > > trace execution flow per client, within reason. And we could do > > similarly for kms clients. > > Could you build such a thing with drm_trace underpinning it, just put the > pertinent information in the message? Not as is. The global has to go, and there's no use for debugfs. So we are just left with a sprintf() around a ring_buffer. I am left in the same position as just wanting to generalise tracek to take the ringbuffer as a parameter. > > Just chiming to say, I don't think a duplicate of dmesg hidden inside > > debugfs achieves much. But a generic tracek-esque ringbuf would be very > > useful -- even if only so we can separate our GEM_TRACE from the global > > tracek. > > I think that's essentially what we've got, I've just narrowly focused on > surfacing debug logs. If drm_trace_printf were exported, replacing > GEM_TRACE would be as simple as s/trace_printk/drm_trace_printf/. Initially I > thought exporting it to drivers would be a bad idea, but I'm open to changing my > mind on this as long as drivers are using it responsibly. I definitely can't make the mistake of flooding kms tracing with overwhelming execution traces -- we can't go back to mixing kms traces with execution traces. -Chris _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
