On Wed, Jul 12, 2017 at 02:49:20PM -0700, Andres Freund wrote: > Hi, > > On 2017-07-11 10:33:37 -0500, Josh Poimboeuf wrote: > > The simpler debuginfo format also enables the unwinder to be much faster > > than DWARF, which is important for perf and lockdep. > > Is this going to be usable for userland call-graphs as well? If one > converts dwarf to that, I mean? Because right now with perf dwarf is > often the only thing that works properly through libc, as libc isn't > compiled with fps and has hardcoded asm not preserving fp. lbr isn't > available for many events, and often not at all available in VMs etc. Just to clarify, these patches are completely separate from DWARF and shouldn't break any existing DWARF-based functionality for user space tooling. So perf can still use DWARF for user space binaries just fine. (Also, tools which rely on CONFIG_DEBUG_INFO for kernel debugging, like gdb and crash, will continue to work.) If you want perf to be able to use ORC instead of DWARF for user space binaries, that's not currently possible, though I don't see any technical blockers for doing so. Perf would need to be taught to read ORC data. And I think it should be possible to convert DWARF to ORC, assuming the DWARF data is trusted. We could probably add an objtool subcommand for that. -- Josh -- To unsubscribe from this list: send the line "unsubscribe live-patching" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
