Re: [PATCH v1 3/8] perf symbol: Fall back to fetching the vmlinux by build ID
From: sashiko-bot@kernel.org
Date: 2026-09-13 02:43:02
From: Arnaldo Carvalho de Melo <redacted> 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 <redacted>
Sashiko has reviewed this patch and found no issues. It looks great! -- Sashiko AI review · https://sashiko.dev/#/patchset/20260913023459.112654-1-acme@kernel.org?part=3