Re: trapped reads in 7.3-rc1 since nv50 instmem handling change

[Jamie Heilman <jamie@audible.transient.net>]

Jamie Heilman wrote:
> On my workstation with a Quadro NVS 290 running 7.3-rc1 I'm seeing
> this sort of thing show up spuriously:
> 
> kernel: nouveau 0000:01:00.0: fb: trapped read at 0100ef56e0 on channel -1 [0fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]
> kernel: nouveau 0000:01:00.0: fb: trapped read at 0100f85788 on channel -1 [0fee0000 unknown] engine 06 [BAR] client 08 [PFIFO_READ] subclient 01 [IN] reason 00000002 [PAGE_NOT_PRESENT]
> (repeated 16 times)
> 
> I bisected it back to 34e27b90552a (nouveau/instmem: use iomapping
> interface for instmem handling).  The rest of the salient dmesg during
> initialization is:
> 
> kernel: nouveau 0000:01:00.0: NVIDIA G86 (086f00a2)
> kernel: nouveau 0000:01:00.0: bios: version 60.86.6c.00.21
> kernel: nouveau 0000:01:00.0: vgaarb: deactivate vga console
> kernel: Console: switching to colour dummy device 80x25
> kernel: nouveau 0000:01:00.0: bios: M0203T not found
> kernel: nouveau 0000:01:00.0: bios: M0203E not matched!
> kernel: nouveau 0000:01:00.0: fb: 256 MiB DDR2
> kernel: nouveau 0000:01:00.0: drm: VRAM: 256 MiB
> kernel: nouveau 0000:01:00.0: drm: GART: 1048576 MiB
> kernel: nouveau 0000:01:00.0: drm: TMDS table version 2.0
> kernel: nouveau 0000:01:00.0: drm: MM: using CRYPT for buffer copies
> kernel: [drm] Initialized nouveau 1.4.3 for 0000:01:00.0 on minor 0
> kernel: Console: switching to colour frame buffer device 240x75
> kernel: nouveau 0000:01:00.0: [drm] fb0: nouveaudrmfb frame buffer device
> 
> It doesn't always happen at boot, sometimes it takes a while to show
> up as it seems to be related to how much I have going on at any point
> in time.  That commit reverts cleanly for the moment, but I'm happy to
> test any ideas or enable further debugging as needed, assuming this
> wasn't intentional.

This is still present after deced5fa01c5 ("nouveau/instmem: handle
iomapping already existing") and in 7.3-rc4.  Apart from the log spam
(which has made journald angry once by flooding the buffer) it doesn't
seem to have any other serious consequences yet though.

-- 
Jamie Heilman                     http://audible.transient.net/~jamie/