Re: ERROR: INT DW_ATE_unsigned_1 Error emitting BTF type

[Yonghong Song]

On 2/5/21 12:31 PM, Sedat Dilek wrote:
> On Fri, Feb 5, 2021 at 9:03 PM Yonghong Song <yhs@xxxxxx> wrote:
> > On 2/5/21 11:24 AM, Arnaldo Carvalho de Melo wrote:
> > > Em Fri, Feb 05, 2021 at 11:10:08AM -0800, Yonghong Song escreveu:
> > > > On 2/5/21 11:06 AM, Sedat Dilek wrote:
> > > > > On Fri, Feb 5, 2021 at 7:53 PM Sedat Dilek <sedat.dilek@xxxxxxxxx> wrote:
> > > > > Grepping through linux.git/tools I guess some BTF tools/libs need to
> > > > > know what BTF_INT_UNSIGNED is?
> > >
> > > > BTF_INT_UNSIGNED needs kernel support. Maybe to teach pahole to
> > > > ignore this for now until kernel infrastructure is ready.
> > >
> > > Yeah, I thought about doing that.
> > >
> > > > Not sure whether this information will be useful or not
> > > > for BTF. This needs to be discussed separately.
> > >
> > > Maybe search for the rationale for its introduction in DWARF.
> >
> > In LLVM, we have:
> >     uint8_t BTFEncoding;
> >     switch (Encoding) {
> >     case dwarf::DW_ATE_boolean:
> >       BTFEncoding = BTF::INT_BOOL;
> >       break;
> >     case dwarf::DW_ATE_signed:
> >     case dwarf::DW_ATE_signed_char:
> >       BTFEncoding = BTF::INT_SIGNED;
> >       break;
> >     case dwarf::DW_ATE_unsigned:
> >     case dwarf::DW_ATE_unsigned_char:
> >       BTFEncoding = 0;
> >       break;
> >
> > I think DW_ATE_unsigned can be ignored in pahole since
> > the default encoding = 0. A simple comment is enough.
>
> Yonghong Son, do you have a patch/diff for me?

Looking at error message from log:

 LLVM_OBJCOPY=/opt/binutils/bin/objcopy /opt/pahole/bin/pahole -J
.tmp_vmlinux.btf
[115] INT DW_ATE_unsigned_1 Error emitting BTF type
Encountered error while encoding BTF.

Not exactly what is the root cause. Maybe bt->bit_size is not
encoded correctly. Could you put vmlinux (in the above it is
.tmp_vmlinux.btf) somewhere, I or somebody else can investigate
and provide a proper fix.

> Thanks.
>
> - Sedat -