Hello, On Wed, 14 Sep 2022, Peter Zijlstra wrote: > > Maybe this is semantics, but I wouldn't characterize objtool's existence > > as being based on the mistrust of tools. It's main motivation is to > > fill in the toolchain's blind spots in asm and inline-asm, which exist > > by design. > > That and a fairly deep seated loathing for the regular CFI annotations > and DWARF in general. Linus was fairly firm he didn't want anything to > do with DWARF for in-kernel unwinding. I was referring only to the check-stuff functionality of objtool, not to its other parts. Altough, of course, "deep seated loathing" is a special form of mistrust as well ;-) > That left us in a spot that we needed unwind information in a 'better' > format than DWARF. > > Objtool was born out of those contraints. ORC not needing the CFI > annotations and ORC being *much* faster at unwiding and generation > (debug builds are slow) were all good. Don't mix DWARF debug info with DWARF-based unwinding info, the latter doesn't imply the former. Out of interest: how does ORC get around the need for CFI annotations (or equivalents to restore registers) and what makes it fast? I want faster unwinding for DWARF as well, when there's feature parity :-) Maybe something can be learned for integration into dwarf-unwind. Ciao, Michael.
