Re: [RFC PATCH v1 0/8] perf/core, perf/tools: Add PERF_SAMPLE_BUILD_ID_OFFSET support

[Peter Zijlstra]

On Fri, Aug 07, 2026 at 12:18:10AM -0700, Ian Rogers wrote:
> This patch series introduces PERF_SAMPLE_BUILD_ID_OFFSET to the
> perf_event UAPI and implements full support across both the kernel
> and perf tools.
> 
> Background & Motivation:
> 
> In order for perf to translate virtual addresses of samples into
> symbols a file and offset within the file are needed. During event
> synthesis perf will create mmap events to facilitate the translation
> of a virtual address to a file and offset by modelling the address
> space of a process. By directly recording in a sample the Build ID of
> a file and the offset within it, no synthesis is necessary. The Build
> ID and offset as a pair are much larger than a virtual address, so
> there is a trade-off between synthesis cost and extra size for
> samples. These changes just facilitate Build ID and offset as a choice
> for perf samples and the user can have the choice to use it when they
> believe it is advantageous.
> 
> In practice perf still needs to map a build ID to a file, so by
> default this change keeps synthesis to allow this. It is expected a
> user that knows their build IDs, say through debuginfod, will disable
> this option with say --synth=no.
> 
> The kernel support uses the existing build ID and offset support used
> by BPF stack traces.

That is still a giant stinking mess that needs to cleaned up.