Quoting Tvrtko Ursulin (2017-12-22 18:52:29)
>
> On 22/12/2017 18:25, Chris Wilson wrote:
> > Looking at a CI failure with an ominous line of
> > [ 362.550715] hangcheck current seqno ffffff6b, last ffffff8c, hangcheck ffffff6b [6016 ms], inflight 118
> > with no apparent cause for the seqno to be negative, left me wondering
> > if someone had scribbled over the HWSP. So include the HWSP in the
> > engine dump to see if there are more signs of random scribbling.
> >
> > v2: Fix row pointer, i is now incremented by 8 so doesn't need scaling
> > by 8, and we don't need to keep volatile here as the status_page isn't
> > marked up as volatile itself.
> > v3: Use hexdump, with suppression of identical lines. (Tvrtko)
> > Which results in
> >
> > HWSP:
> > 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > *
> > 00000040 00000001 00000000 00000018 00000002 00000001 00000000 00000018 00000000
> > 00000060 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000003
> > 00000080 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > *
> > 000000c0 00000002 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > 000000e0 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
> > *
> >
> > instead of 128 lines of mostly 0s.
> > v4: Tidy up the locals
> >
> > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> > Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
> > Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> #v2
> > ---
> > drivers/gpu/drm/i915/intel_engine_cs.c | 31 ++++++++++++++++++++++++++++++-
> > 1 file changed, 30 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
> > index 9856e24c7c43..5eefd420f709 100644
> > --- a/drivers/gpu/drm/i915/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c
> > @@ -1667,6 +1667,32 @@ static void print_request(struct drm_printer *m,
> > rq->timeline->common->name);
> > }
> >
> > +static void hexdump(struct drm_printer *m, const void *buf, size_t len)
> > +{
> > + const size_t rowsize = 8 * sizeof(u32);
> > + const void *prev = NULL;
> > + bool skip = false;
> > + size_t row;
>
> offset or pos ? Row makes me think it is row-indexed but it is bytes.
pos then. It's the start of the row, but it I felt uncomfortable with
it being an offset.
> > +
> > + for (row = 0; row < len; row += rowsize) {
> > + char line[128];
>
> Could dial down the size wrt stack use. 8 * 8 = 64 + 7 spaces + null =
> 72 should be enough.
But 72 is not a power-of-two!
> > +
> > + if (prev && !memcmp(prev, buf + row, rowsize)) {
> > + if (!skip) {
> > + drm_printf(m, "*\n");
> > + skip = true;
> > + }
> > + continue;
> > + }
> > +
> > + hex_dump_to_buffer(buf + row, len - row, rowsize, sizeof(u32),
> > + line, sizeof(line), false);
>
> Future proof by a WARN_ON_ONCE(ret >= sizeof(line)) ?
Actually had a WARN_ON for testing, seems reasonable to stick one back
in.
> > + drm_printf(m, "%08zx %s\n", row, line);
> > + prev = buf + row;
> > + skip = false;
> > + }
> > +}
> > +
> > void intel_engine_dump(struct intel_engine_cs *engine,
> > struct drm_printer *m,
> > const char *header, ...)
> > @@ -1869,8 +1895,11 @@ void intel_engine_dump(struct intel_engine_cs *engine,
> > &engine->irq_posted)),
> > yesno(test_bit(ENGINE_IRQ_EXECLIST,
> > &engine->irq_posted)));
> > +
> > + drm_printf(m, "HWSP:\n");
> > + hexdump(m, engine->status_page.page_addr, PAGE_SIZE);
> > +
> > drm_printf(m, "Idle? %s\n", yesno(intel_engine_is_idle(engine)));
> > - drm_printf(m, "\n");
> > }
> >
> > static u8 user_class_map[] = {
> >
>
> Looks okay - with or without the tweaks:
>
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
Ta, enjoy your break.
-Chris
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