On 04/09/2023 06:05, Linu Cherian wrote:
This RFC v3 patch series is rebased on v6.5-rc7 and is dependent on the below two patches.
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Steps for reading trace data captured in previous boot ++++++++++++++++++++++++++++++++++++++++++++++++++++++
cd /sys/bus/coresight/devices/tmc_etrXX/
Change to special mode called, read_prevboot.
#echo 1 > read_prevboot
Dump trace buffer data to a file,
#dd if=/dev/tmc_etrXX of=~/cstrace.bin
Hi Linu,
I left this comment on V2, but I tested it again and get the same result. Instead of linking it I'll just re-paste it here:
I made a reserved region, but when I run this command I get "Unable to handle kernel paging request at virtual address 001f1921ed10ffae".
Is there an extra step involved if there was no trace captured from a previous panic? I thought I'd just be able to read out uninitialised data. Or is it the uninitialised metadata that's causing this issue?
Also that's without KASAN or lockdep turned on. If I have a kernel with either of those things I get a different warning for each one. I expect the lockdep one would happen even in the working scenario though?
Reset back to normal mode
#echo 0 > read_prevboot