Hi Chris,
On Thu, Jun 21, 2018 at 6:45 PM Chris Brandt <Chris.Brandt@xxxxxxxxxxx> wrote:
> On Thursday, June 21, 2018 1, Nicolas Pitre wrote:
> > > I've just sent a patch to do that.
> >
> > Your patch isn't wrong per se. But it is not enough. The issue here
> > would be easily fixed with some kconfig extension so that:
> >
> > - If XIP or NOMMU is selected then only one target in the multiplatform
> > set can be selected, basically turning it into a choice menu.
> >
> > - If more than one multiplatform targets is selected then XIP and NOMMU
> > can no longere be selected.
>
> Over the years I tried to tackle this issue in multiple different ways,
> while still staying in the limitations of kbuild.
> Basically, everything was shot down for one reason or another (or the
> only way to do it is really ugly...so I didn't even ask).
>
> kbuild doesn't really have a mutually exclusive property that can be
> dynamically set/cleared.
>
> In the end, I saw only 2 paths for adding XIP to ARM MMU builds:
>
> 1) Modify kbuild to give the ability as stated above.
Would that actually help, or would it only give you a false feeling of safety?
Most "multiplatform" sub-architectures (like iMX or "shmobile") still have
multiple families and SoCs, so you have to repeat the exercise at that level.
Still, even when configuring a kernel for a single SoC, the final board
selection is at the DTS level.
Conclusion: If you want NOMMU and/or XIP, you have to know what you're doing,
and hand-holding at whatever level may not save you from making mistakes.
> 2) Make XIP builds somehow be able to run at multiple physical address
> by modifying the binaries post-build (Arnd's suggestion).
That's actually an interesting one: no manual configuration (iff parameters
would be extracted from the DTB), so nothing can go wrong ;-)
I guess it applies to NOMMU, too.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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