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Re: PATCH: Turn on -fomit-frame-pointer by default for 32bit Linux/x86
On Wed, 4 Aug 2010, Andi Kleen wrote:
> > Can we find if oprofile works with -fomit-frame-pointer on 32bit Linux/x86.
> It doesn't for user space. The problem is that you would need
> an in kernel dwarf2 unwinder that reads user space tables.
> x86-64 suffers from this already.
> However there are some alternative approaches being explored for this,
> like using LBRs.
I don't know what a LBR is, but FWIW, it looks to me like a scenario
asking for a userspace daemon interpreting raw address/stack information
passed on from the kernel. The daemon could use whatever complex tools
are needed to interpret the information received or just dump it somewhere
in a form complete enough for later post-processing (e.g. if the tools
required were not fast enough to cope in real time).
Just because while in some cases it seems easier to code (hack) things
into the kernel, it does not necessarily mean they should be there. The
fewer things in the kernel the better. Just IMHO.