Em Sat, Sep 03, 2022 at 07:26:58AM +0200, Greg KH escreveu: > On Fri, Sep 02, 2022 at 06:51:00PM +0200, Jiri Olsa wrote: > > On Sun, Aug 28, 2022 at 08:33:17PM -0300, Martin Rodriguez Reboredo wrote: > > > After the release of pahole 1.24 some people in the dwarves mailing list > > > notified issues related to building the kernel with the BTF_DEBUG_INFO > > > option toggled. They seem to be happenning due to the kernel and > > > resolve_btfids interpreting btf types erroneously. In the dwarves list > > > I've proposed a change to the scripts that I've written while testing > > > the Rust kernel, it simply passes the --skip_encoding_btf_enum64 to > > > pahole if it has version 1.24. > > > > > > v1 -> v2: > > > - Switch to off by default and remove the config option. > > > - Send it to stable instead. > > > > hi, > > we have change that needs to go to stable kernels but does not have the > > equivalent fix in Linus tree > > Why isn't it also relevant in Linus's tree? See below. > > what would be the best way to submit it? > > Submit it here and document the heck out of why this isn't in Linus's > tree, what changes instead fixed it there, and so on. Look in the > archives for examples of how this is done, one recent one that I can > think of is here: > https://lore.kernel.org/r/20220831191348.3388208-1-jannh@xxxxxxxxxx > > > the issue is that new 'pahole' will generate BTF data that are not supported > > by older kernels, so we need to add --skip_encoding_btf_enum64 option to > > stable kernel's scripts/pahole-flags.sh to generate proper BTF data > > > > we got complains that after upgrading to latest pahole the stable kernel > > compilation fails > > And what is happening in Linus's tree for this same issue? So, BTF_KIND_ENUM64 is a new BTF tag, one that is not accepted by older kernels, but is accepted by the BPF verifier on Linus' tree. Its about avoiding having a pahole command line with lots of --enable-new-feature-foo for new stuff with the default producing the most recent BTF spec. One way to documenting it: if you update pahole, then please use --skip_encoding_FOO for these new FOO features on kernels where those aren't supported. So this isn't a backport from a fix on Linus' tree, as both the older pahole that doesn't encode BTF_KIND_ENUM64 and the new one, that encodes it by default, work with Linus' tree. Does this violates the stable@ rules? - Arnaldo
