Re: [PATCH] automation: Add Arm64 MPU build job

["Anthony PERARD" <anthony.perard@vates.tech>]

On Thu, Apr 03, 2025 at 12:00:39PM +0200, Jan Beulich wrote:
> On 03.04.2025 11:35, Orzel, Michal wrote:
> > A different question (also to other people who knows this stuff).
> > MPU requires to specify Xen start address using CONFIG_XEN_START_ADDRESS that is
> > set to invalid default value to catch user attention. Provided that randconfig
> > can select UNSUPPORTED and MPU, we should somehow set CONFIG_XEN_START_ADDRESS
> > to e.g. 0 to be able to build successfully. Is this where we need to add
> > EXTRA_FIXED_RANDCONFIG to existing arm64 and arm32 randconfig jobs?
> 
> In principle some override like this will be needed, I think, yet that undermines
> the randomness of the build. From what I can tell the sole constraint on
> XEN_START_ADDRESS is that it needs to be page aligned (for whatever reason; I
> didn't think there was the concept of "pages" without an MMU [1]). Arbitrary
> values satisfying this constraint ought to be selectable by random configurations.
> Which would then - hopefully - also trigger the case where XEN_START_ADDRESS is
> e.g. so large that Xen can't fit in the remaining address space anymore. Plus
> perhaps any other constraints presently not enforced.
> 
> How to deal with all of this, i.e. how to leave as much flexibility as possible
> to randconfig, I simply don't know. Extending the Cc list in the hope for someone
> to provide some insight.

It doesn't looks like kconfig have support for randomizing hex values.
So you'll have to provide a value for XEN_START_ADDRESS that actually
respect the contrain written in prose, since the default doesn't.

Ah, the prompt of that config value is way to long and contain
explanation that ought to be in the help message instead. So I guess the
default value is the choose default value option, so probably fine for
randconfig.

Cheers,

-- 

Anthony Perard | Vates XCP-ng Developer

XCP-ng & Xen Orchestra - Vates solutions

web: https://vates.tech