Re: [PATCH] tcg/tci: Fix TCI on hppa host and update TCI test matrix

[Helge Deller]

On 1/7/24 16:22, Peter Maydell wrote:
> On Sun, 7 Jan 2024 at 07:20, Helge Deller <deller@kernel.org> wrote:
> > Update the TCI interpreter test matrix for big-endian hosts with
> > big- (hppa, hppa64) and little-endian (x86,x96-64) targets.
> > I used native ppc64 and hppa hosts for those tests.
> >
> > Starting TCI on a hppa host crashed immediately, because hppa is
> > the only archive left where the stack grows upwards.
> > Write-protecting the stack guard page at the top of the stack
> > fixes the crash.
>
> We deliberately dropped support for HPPA hosts, under
> commit a1eaa6281f8b and commit b1cef6d02f84bd8.
> Do we really care enough about trying to run on these
> ancient host CPUs to want to bring it back?
>
> My personal rule of thumb is that if a host CPU is supported
> only by TCI then we are better off saying it is entirely
> unsupported -- in practice the performance will be so
> terrible as to not be something anybody will want to use,
> especially for older architectures which are slow to
> start with.

I can see your point (and the performance is really horrible).
It's not my intention to make hppa a supported TCI platform,
but for me it's a good candidate to at least test TCI on
a big-endian machine, mostly because I have access to some of
such machines.
And, this patch is all what's needed and it's pretty trivial, so
it would be great if it could be accepted.

Helge