Re: [RFC] Testing 7.1.0-rc2, qemu-ppc does not give valid disassembly

[Peter Maydell]

On Thu, 11 Aug 2022 at 14:35, Pierre Muller <pierre@freepascal.org> wrote:
>    I don't know if this is the right place to submit this report,
> but I have a problem with my attempt to check the 7.1.0 release candidate
> for linux user powerpc CPU.
>
>    I am testing a simple executable, compiled with Free Pacal compiler,
> but also linked to libc.
>
> This is what I obtain with the new rc:
>
> ~/gnu/qemu/build-qemu-7.1.0-rc1/qemu-ppc -L ~/sys-root/powerpc-linux -d 
> in_asm tprintf
> ----------------
> IN: _start
> 0x3ffda784:
> OBJD-T: 7c230b78388000003821fff0908100004bfe756d

This is because you don't have the libcapstone development package
installed on your host system.

>    I did find that this is related to the fact that
> upon configuration, meson finds no capstone library,
> while disassembly of powerpc CPU has been moved to use of
> capstone in this commit:

The other relevant commit here is

commit 83602083b4ada6ceb86bfb327e83556ebab120fc
Author: Thomas Huth <thuth@redhat.com>
Date:   Mon May 16 16:58:23 2022 +0200

    capstone: Remove the capstone submodule

    Now that we allow compiling with Capstone v3.0.5 again, all our supported
    build hosts should provide at least this version of the disassembler
    library, so we do not need to ship this as a submodule anymore.

> Even when trying to compile the git checkout,
> which contains capstone as a sub-module, in capstone sub-directory,
> I always get capstone support set to NO by meson configuration.

If your git checkout still has a capstone subdirectory this
is an old leftover from a checkout that predated 83602083b4ada.
('git status' will tell you this, and a suitable 'git clean'
command will get rid of it for you.)

> Why doesn't it use the sub-module if pkg-config says that there
> is not system capstone library installed?

Because we now can rely on all our supported host distributions
being modern enough to ship libcapstone, and we don't need to
cart around a submodule any more (which reduces our maintenance
burden). As Cédric suggests, you can pass '--enable-capstone'
to configure if you would like configure to fail if it can't
find the system libcapstone, rather than falling back to the
binary-blob disassembler.

thanks
-- PMM