On 15/06/16 16:34, Arnaldo Carvalho de Melo wrote: > Em Tue, May 17, 2016 at 09:04:54AM +0000, He Kuang escreveu: >> There's a problem in machine__findnew_vdso(), vdso buildid generated >> by a 32-bit machine stores it with the name 'vdso', but when >> processing buildid on a 64-bit machine with the same 'perf.data', perf >> will search for vdso named as 'vdso32' and get failed. > > Without looking at the code, just trying to understand your patch by > reading your description: Why would we look for names if we have > build-ids? All this type and name comparasions seems wrong if we have a > build-id, no? > > Adrian?
We match maps to builds ids using the file name - consider machine__findnew_[v]dso() called in map__new(). So in the context of a perf data file, we consider the file name to be unique. A vdso map does not have a file name - all we know is that it is vdso. We look at the thread to tell if it is 32-bit, 64-bit or x32. Then we need to get the build id which has been recorded using short name "[vdso]" or "[vdso32]" or "[vdsox32]". The problem is that on a 32-bit machine, we use the name "[vdso]". If you take a 32-bit perf data file to a 64-bit machine, it gets hard to figure out if "[vdso]" is 32-bit or 64-bit. This patch solves that problem. I acked it in another email.
