Re: [PATCH 3/9] perf symbol: Fall back to fetching the vmlinux by build ID

[sashiko-bot@kernel.org]

> From: Arnaldo Carvalho de Melo <acme@redhat.com>
> 
> A profile recorded on a kernel that is no longer installed, be it
> because the machine was rebooted into a new kernel or because the
> profile is being processed on another machine, can't have its kernel
> symbols resolved: /proc/kallsyms matches the running kernel, not the
> one in the profile, and is refused when restricted, e.g. with
> kernel.perf_event_paranoid > 1, while the build-id cache may carry
> just a kallsyms copy with zeroed addresses.  With no kernel symbols
> the kernel samples can't be annotated, so they all end up in the
> '(unknown)' data type and the kernel is missing from the data type
> profile JSON "dsos" entry.
> 
> As a last resort, when the kernel symbols can't be found locally and
> the user didn't specify a kallsyms file, fetch the vmlinux keyed by
> [ ... ]
> struct tty_struct, struct qspinlock, etc, with the kernel DSO, keyed
> by its build ID, appearing in the data type profile JSON.
> 
> Assisted-by: LLM
> Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.dev/#/patchset/20260914125451.2045-1-acme@kernel.org?part=3