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[DRAFT][TEST][DNM] Super early trace - #4758
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keyonjie
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Sep 14, 2021
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As reported in thesofproject#4759, thesofproject#4636 and a few others linked from there. Signed-off-by: Marc Herbert <marc.herbert@intel.com>
This reverts commit 7df3674. This restores the ability to use CONFIG_TRACEM (copy everything to mailbox) without crashing, in other words it fixesthesofproject#4699 This also fixes the other DSP panic thesofproject#4676 and removes the need for logical changes in thesofproject#4678, which can be reverted too. commit 7df3674 ("trace: enable trace after it is ready") was meant to fix a crash when tr_xxx() was used early. However I've used very early tracing for months and it never caused any crash (see thesofproject#4334) I tried adding a tr_err() statement immediately after trace_init(sof) in primary_core_init() and it works just fine. primary_core_init() runs extremely early so I don't think it's too demanding not to use an tr_XXX() before the trace even exists. The reverted commits confused initializing and enabling. Reproduction thesofproject#4683 did not seem to demonstrate anything obvious, there's not even a link to a failed test run. I don't understand how playing with spin locks is relevant to this. Later, reproduction thesofproject#4759 finally demonstrated the real issue: through DEBUG_TRACE_PTR(), some tr_XXX() can indeed be called (in very unusal debug circumstances specific to the original author) before the trace is initialized. The previous commit in this series fixes that by simply guarding it with if(trace_get()) -------- I am _not_ pretending that these reverts make the tracing code bug-free and perfect again, absolutely not and very far from it. I'm merely saying that: - The first reverted commit caused at least two regressions: thesofproject#4676 and thesofproject#4699 - These two commits added yet another variable (time) in an already complex situation with an already existing combinatorial "explosion": compile-time Kconfigs, run-time settings, platform-specific bugs (thesofproject#4333, thesofproject#4573, ...), various races, mbox + DMA, different DMA engines, Zephyr vs XTOS, etc. - Last but not least, we don't want to invest in making the exist trace implementation better. We want to switch to the Zephyr implementation instead So let's go back to a previous known good state, I mean _relatively_ good and stay there if we can. Signed-off-by: Marc Herbert <marc.herbert@intel.com>
This shows that thesofproject#4636 did not fix any real-world issue. thesofproject#4636 changed some sof->trace logic, however sof->trace does not exist before trace_init() and calling tr_err() immediately after trace_init() works. Note DSP panics were detected immediately after thesofproject#4636 was merged, see reports in thesofproject#4676 Signed-off-by: Marc Herbert <marc.herbert@intel.com>
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09c389cCompareNo crash when guarded with if(trace_get()) Signed-off-by: Marc Herbert <marc.herbert@intel.com>
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Sep 14, 2021
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https://sof-ci.01.org/sofpr/PR4758/build10325/devicetest/?model=BDW_WSB_RT286&testcase=check-sof-logger is the old stuck DMA issue #4333. Everything else is green and shows Example: Older https://sof-ci.01.org/sofpr/PR4758/build10320/devicetest/ is all green and tests show the expected in the mailbox trace: More DEBUG_TRACE_PTR() testing in the 3rd force push. |
marc-hb
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Sep 14, 2021
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https://sof-ci.01.org/sofpr/PR4758/build10327/devicetest/ is all green and is has the expected traces, for instance in https://sof-ci.01.org/sofpr/PR4758/build10327/devicetest/?model=CML_RVP_SDW&testcase=check-sof-logger |
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Purely for extra testing of #4760