Re: [PATCH v5 0/3] Use BTF to trim return values

From: Google

Date: Wed Sep 02 2026 - 11:13:39 EST


On Wed, 2 Sep 2026 11:25:29 +0800
Peng Donglin <dolinux.peng@xxxxxxxxx> wrote:

> >> - Do not print a return value for functions with a void return type.
> >> - Trim integer, enum, struct, and union values to the available return
> >> value width when the BTF type provides suitable size information.
> >> - Format integer, enum, and boolean values according to their BTF
> >> encoding.
> >> - Mark values as "(trunc)" when the return type is wider than the
> >> value captured by the function graph tracer.
> >
> > Hmm, I really don't like the "(trunc)" If it's the real return type, then
> > it should just print what the real size is. No need to state it was truncated.
>
> Thanks, I agree. We can remove the "(trunc)" suffix and print the actual
> type information instead, for example:
>
> ret=0x5[struct:0x10]
>
> This would indicate that the return type is a struct with a size of 0x10
> bytes.

Hmm, shouldn't both the actually applied size and the true size be displayed?
e.g.

ret=0x5 (in 8 bytes, true size: 16 bytes)

Thank you,

>
> Would this be acceptable?
>
> >

--
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>