Re: [PATCH] perf build: Fix compiler errors with old capstone

[Ian Rogers]

On Wed, Jul 1, 2026 at 12:30 PM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
>
> Hi Ian,
>
> On Wed, Jul 01, 2026 at 11:49:03AM -0700, Ian Rogers wrote:
> > On Wed, Jul 1, 2026 at 11:28 AM Namhyung Kim <namhyung@xxxxxxxxxx> wrote:
> > >
> > > It seems RISCV was added in capstone version 5.  Unfortunately they are
> > > enum constants so cannot check with #ifdef but anyway we can define the
> > > symbols.  Let's do it using the version number to avoid build errors.
> > > It'll fail at runtime though.
> > >
> > >   util/capstone.c: In function 'e_machine_to_capstone':
> > >   util/capstone.c:186:25: error: 'CS_ARCH_RISCV' undeclared (first use in this function);
> > >                                   did you mean 'CS_ARCH_SYSZ'?
> > >     186 |                 *arch = CS_ARCH_RISCV;
> > >         |                         ^~~~~~~~~~~~~
> > >         |                         CS_ARCH_SYSZ
> > >   util/capstone.c:186:25: note: each undeclared identifier is reported only once for each function it appears in
> > >
> > >   util/capstone.c:187:34: error: 'CS_MODE_RISCV64' undeclared (first use in this function);
> > >                                   did you mean 'CS_MODE_MIPS64'?
> > >     187 |                 *mode |= (is64 ? CS_MODE_RISCV64 : CS_MODE_RISCV32) | CS_MODE_RISCVC;
> > >         |                                  ^~~~~~~~~~~~~~~
> > >         |                                  CS_MODE_MIPS64
> > >
> > > Also note that capstone renamed CS_MODE_RISCVC to CS_MODE_RISCV_C which
> > > would cause a different build failure on latest versions.  It's reported
> > > in https://github.com/capstone-engine/capstone/issues/2977 so I think
> > > they will add compatibility layer to prevent the error.
> > >
> > > Fixes: 12c4737f55f2 ("perf capstone: Determine architecture from e_machine")
> > > Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
> >
> > Perhaps update the feature test from:
> > https://web.git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/build/feature/test-libcapstone.c?h=perf-tools-next
> > ```
> > cs_open(CS_ARCH_X86, CS_MODE_64, &handle);
> > ```
> > to be CS_ARCH_RISCV? That way we won't detect old libcapstones and
> > avoid cluttering up the code.
>
> Then it'll drop support for capstone version 4 which works fine on some
> architectures.  Maybe we can add another feature check for capstone
> RISC-V support but I think it's better to define the RISCV symbols here.
>
> What do you think?

Arnaldo and I also discussed this in a thread, but I can't find it
right now. I believe the RISC-V support in libcapstone is now 8 years
old:
https://github.com/capstone-engine/capstone/issues/966
so it seemed unfortunate to add shims to support older libcapstone versions.

Thanks,
Ian

> Thanks,
> Namhyung
>