Messages in this thread | | | Date | Wed, 16 Feb 2022 15:51:31 +1100 | Subject | Re: [RFC PATCH kernel] trace: Make FTRACE_MCOUNT_USE_RECORDMCOUNT configurable | From | Alexey Kardashevskiy <> |
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On 2/15/22 03:10, Sami Tolvanen wrote: > On Fri, Feb 11, 2022 at 4:11 PM Nick Desaulniers > <ndesaulniers@google.com> wrote: >> >> + Sami, Kees >> >> Do you guys remember why we don't support >> FTRACE_MCOUNT_USE_RECORDMCOUNT with LTO? > > It's because recordmcount cannot distinguish between calls and other > references to mcount/fentry, which is a problem with LTO where we have > to process the entire vmlinux.o and cannot ignore individual > translation units. Instead of resorting to workarounds, Peter was kind > enough to implement a smarter mcount pass in objtool, which we now use > on x86_64 with LTO.
So can x86_64 have both FTRACE_MCOUNT_USE_RECORDMCOUNT and LTO?
> Alexey, which architecture are you trying to fix here?
powerpc64le.
> > Sami
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