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

[Namhyung Kim <namhyung@kernel.org>]

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@kernel.org> 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@kernel.org>
> 
> 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?

Thanks,
Namhyung