22:03 <agentzh> fche: it seems like stap does not bother using .debug files for userland stack unwinding? it just uses the elf sections .eh_frame and .eh_frame_hdr for that?

22:03 <fche> it can use .debug_frame if .eh_frame is not there

22:03 <fche> usually the binaries have one or the other, not both

22:04 <agentzh> ok, i see. thanks

22:06 <agentzh> fche: i wonder if it is required to use exactly the same version of gcc to build the stap kernel module as the one used to build the current running kernel.

22:06 <agentzh> or just using the same major series of gcc is fine.

22:06 <agentzh> like gcc 4.8.x or 5.x.

22:09 <fche> agentzh, generally it should be the same compiler, because the kernel configuration & header machinery sometimes does compiler version sensitive changes to structs etc., which break the abi

22:09 <fche> same rules as for building any out-of-tree module

22:10 <agentzh> yeah, i used to run into such ABI breakage in the past, hence the question.

22:10 <agentzh> wondering if the same gcc series wouldn't break that.

22:10 <agentzh> otherwise installing different versions of gcc for a lot of machines running stap is painful.

22:10 <agentzh> hopefully we can do some sort of "cross-compilation" here.

22:11 <agentzh> like stap -r DIR.

22:11 <fche> there is stap -B FOO_ to prefix compiler tools with something

22:13 <agentzh> yeah, that would be useful.

22:13 <agentzh> at least do not have to uninstall the default gcc.

22:13 <agentzh> but still we'll have to install a lot of different versions of gcc.

22:15 <agentzh> if we could just always use the latest version of gcc of the same series in a single distro, then it would be great.

22:17 <fche> run a stap compile server per distro

22:18 <fche> hm

22:18 <fche> we had earlier worked on a stap multi-compile-server prototype, whereby a single instance of stap-serverd would be able to spin up a docker buildroot for any arbitrary target os version, and run the build inside that

22:18 <fche> didn't quite finish it tho

22:18 <fche> you can see it in the source tree, httpd/ subdirectory