Re: [PATCH v4 2/5] docs/about/deprecated: Deprecate the qemu-system-i386 binary

[Thomas Huth <thuth@xxxxxxxxxx>]

On 06/03/2023 15.06, Daniel P. Berrangé wrote:
> On Mon, Mar 06, 2023 at 02:48:16PM +0100, Thomas Huth wrote:
> > On 06/03/2023 10.27, Daniel P. Berrangé wrote:
> > > On Mon, Mar 06, 2023 at 09:46:55AM +0100, Thomas Huth wrote:
> > > > [...] If a 32-bit CPU guest
> > > > +environment should be enforced, you can switch off the "long mode" CPU
> > > > +flag, e.g. with ``-cpu max,lm=off``.
> > > I had the idea to check this today and this is not quite sufficient,
> > [...]
> > > A further difference is that qemy-system-i686 does not appear to enable
> > > the 'syscall' flag, but I've not figured out where that difference is
> > > coming from in the code.
> > I think I just spotted this by accident in target/i386/cpu.c
> > around line 637:
> >
> > #ifdef TARGET_X86_64
> > #define TCG_EXT2_X86_64_FEATURES (CPUID_EXT2_SYSCALL | CPUID_EXT2_LM)
> > #else
> > #define TCG_EXT2_X86_64_FEATURES 0
> > #endif
> Hmm, so right now the difference between qemu-system-i386 and
> qemu-system-x86_64 is based on compile time conditionals. So we
> have the burden of building everything twice and also a burden
> of testing everything twice.
>
> If we eliminate qemu-system-i386 we get rid of our own burden,
> but users/mgmt apps need to adapt to force qemu-system-x86_64
> to present a 32-bit system.
>
> What about if we had qemu-system-i386 be a hardlink to
> qemu-system-x86_64, and then changed behaviour based off the
> executed binary name ?
We could also simply provide a shell script that runs:

 qemu-system-x86_64 -cpu qemu32 $*

... that'd sounds like the simplest solution to me.

 Thomas