On Thu, Feb 5, 2026 at 8:10 PM Donglin Peng <[email protected]> wrote:
>
> On Thu, Feb 5, 2026 at 11:56 PM Alexei Starovoitov
> <[email protected]> wrote:
> >
> > On Thu, Feb 5, 2026 at 1:21 AM Donglin Peng <[email protected]> wrote:
> > >
> > > On Wed, Feb 4, 2026 at 10:52 PM Donglin Peng <[email protected]> 
> > > wrote:
> > > >
> > > > On Wed, Feb 4, 2026 at 12:00 AM Alexei Starovoitov
> > > > <[email protected]> wrote:
> > > > >
> > > > > On Tue, Feb 3, 2026 at 7:16 AM Steven Rostedt <[email protected]> 
> > > > > wrote:
> > > > > >
> > > > > > On Tue, 3 Feb 2026 21:50:47 +0800
> > > > > > Donglin Peng <[email protected]> wrote:
> > > > > >
> > > > > > > Testing revealed that sorting within resolve_btfids introduces 
> > > > > > > issues with
> > > > > > > btf__dedup. Therefore, I plan to move the sorting logic directly 
> > > > > > > into
> > > > > > > btf__add_enum_value and btf__add_enum64_value in libbpf, which are
> > > > > > > invoked by pahole. However, it means that we need a newer pahole
> > > > > > > version.
> > > > > >
> > > > > > Sorting isn't a requirement just something I wanted to bring up. If 
> > > > > > it's
> > > > > > too complex and doesn't achieve much benefit then let's not do it.
> > > > > >
> > > > > > My worry is because "cat trace" takes quite a long time just 
> > > > > > reading the
> > > > > > BTF arguments. I'm worried it will just get worse with enums as 
> > > > > > well.
> > > > > >
> > > > > > I have trace-cmd reading BTF now (just haven't officially released 
> > > > > > it) and
> > > > > > doing an extract and reading the trace.dat file is much faster than 
> > > > > > reading
> > > > > > the trace file with arguments. I'll need to implement the enum 
> > > > > > logic too in
> > > > > > libtraceevent.
> > > > >
> > > > > If you mean to do pretty printing of the trace in user space then +1 
> > > > > from me.
> > > > >
> > > > > I don't like sorting enums either in resolve_btfid, pahole or kernel.
> > > > > Sorted BTF by name was ok, since it doesn't change original semantics.
> > > > > While sorting enums by value gets us to the grey zone where
> > > > > the sequence of enum names in vmlinux.h becomes different than in 
> > > > > dwarf.
> > > >
> > > > Thanks, I agreed.
> > > >
> > > > >
> > > > > Also id->name mapping in general is not precise.
> > > > > There is no requirement for enums to be unique.
> > > > > Just grabbing the first one:
> > > > > ATA_PIO0 = 1,
> > > > > ATA_PIO1 = 3,
> > > > > ATA_PIO2 = 7,
> > > > > ATA_UDMA0 = 1,
> > > > > ATA_UDMA1 = 3,
> > > > > ATA_UDMA2 = 7,
> > > > > ATA_ID_CYLS = 1,
> > > > > ATA_ID_HEADS = 3,
> > > > > SCR_ERROR = 1,
> > > > > SCR_CONTROL = 2,
> > > > > SCR_ACTIVE = 3,
> > > > >
> > > > > All these names are part of the same enum type.
> > > > > Which one to print? First one?
> > >
> > > Another option is to print all matching entries, incurring increased
> > > overhead and extended trace log length. However, I prefer printing
> > > the first matching entry, though it might be inaccurate in rare cases.
> >
> > I disagree. It's not rare.
> > I wouldn't print anything. Let user space deal with it.
>
> Okay, I will implement this in libtraceevent first. By the way, would the 
> first
> patch [1] introducing the for_each_enumand for_each_enum64 helper
> macros be acceptable?
>
> [1] 
> https://lore.kernel.org/lkml/[email protected]/

Just that patch alone? What's the point?
Refactor for what? Does it read better? No.

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