Thanks Mark, On Tue, 2020-10-27 at 15:39 +0100, Mark Wielaard wrote: > The basic idea behind getting buildids into core files is that they > (the GNU ELF notes) are at the start of the file in the first page > that is dumped (together with the phdrs) in the core file so when > core file consumers can walk the program headers and find the buildid > note (almost immediately following those headers).
Something is missing; if I check the binary I see a build ID in it. I can control whether the userspace coredumper or the kernel coredumper is used via an environment variable: the kernel-generated core contains a full set of build ID values including vdso.so, the binary, and all normal .so's. But when using the userspace coredumper I get a completely valid coredump that GDB is happy with, for example, but there is only the vdso.so build ID present: I don't see any build IDs from the binary or shared libraries. I guess another possibility is that they are there but eu-unstrip --core can't find them? The userspace coredumper uses the output of /proc/self/maps and /proc/self/smaps to determine what memory to dump; the code is a bit hairy but I will investigate what's going on. The parsing of the maps starts here (I don't really expect anyone to read this but if you're curious): https://github.com/madscientist/google-coredumper/blob/1b64fbc282ba08654853f34c2bda00ffe5e26855/src/elfcore.c#L760 and the write-out starts here: https://github.com/madscientist/google-coredumper/blob/1b64fbc282ba08654853f34c2bda00ffe5e26855/src/elfcore.c#L1019 > A few more technical details can be found at: > https://fedoraproject.org/wiki/Releases/FeatureBuildId#Include_build_IDs_in_core_dumps Thanks I did see that but I will read it harder.
