Em Wed, Sep 16, 2020 at 04:17:00PM +0200, [email protected] escreveu: > On Wed, Sep 16, 2020 at 11:07:44AM -0300, Arnaldo Carvalho de Melo wrote: > > Em Wed, Sep 16, 2020 at 10:20:18AM +0200, Jiri Olsa escreveu: > > > > > IIRC BUILD_ID_SIZE is 20 bytes which is the correct size for SHA-1. A > > > > build ID may be 128-bits (16 bytes) if md5 or uuid hashes are used. > > > > Should this test just be "> 0" ? > > > > > > ah right, will check on that > > > > And how do you deal with this in the kernel? I.e. to inform userspace, > > via the PERF_RECORD_MMAP3 (or MMAP2 with that misc bit trick) the size > > of the build-id? > > The union size is 24 bytes, so there's plenty space to store a length > field with the buildid.
So, I think we should instead use a bit in the misc field, stating the kind of build-id, so that we don't waste a byte for that, I think. - Arnaldo
