Re: [RFC PATCH v2 00/17] objtool: Function validation tracing

[Alexandre Chartre]

On 9/24/25 12:10, Peter Zijlstra wrote:
> On Wed, Sep 24, 2025 at 12:08:47PM +0200, Peter Zijlstra wrote:
> > On Wed, Sep 24, 2025 at 09:42:06AM +0200, Peter Zijlstra wrote:
> >
> > > > >    d051:  perf_get_x86_pmu_capability+0x51    | xchg   %ax,%ax
> >
> > That libopcode is 'funny', isn't that typically spelled "nop" ?
>
> Ooh, I see, it is "osp nop" and yeah binutils also seems to do that as
> "xchg %ax,%ax".

Yes, "xchg %ax,%ax" is NOP2 (opcodes: 0x66 0x90), "nop" is NOP1 (0x90).

That's one more improvement we can do: identify NOP instructions and
display them as NOP<n>

alex.