Re: [PATCH 2/2] xen/arm32: head: Improve logging in head.S

[Julien Grall <julien@xxxxxxx>]

On 02/11/2023 10:23, Michal Orzel wrote:
> >           /* Address in the runtime mapping to jump to after the MMU is enabled 
> > */
> >           mov_w lr, primary_switched
> > @@ -593,6 +603,21 @@ enable_mmu:
> >           mcr   CP32(r0, HSCTLR)       /* now paging is enabled */
> >           isb                          /* Now, flush the icache */
> >
> > +        /*
> > +         * At this stage, the UART address will depend on whether the
> > +         * temporary mapping was created or not.
> > +         *
> > +         * If it was, then the UART will be mapped in the temporary
> > +         * area. Otherwise, it will be mapped at runtime virtual
> > +         * mapping.
> > +         */
> > +#ifdef CONFIG_EARLY_PRINTK
> > +        teq   r12, #1               /* Was the temporary mapping created? */
> > +        mov_w_on_cond eq, r11, TEMPORARY_EARLY_UART_VIRTUAL_ADDRESS
> Shouldn't the clobber list be updated?
I missed this comment. I understand it will get clobbered today, but 
thinking a bit more, I would actually prefer if r11 is updated to 
EARLY_UART_ADDRESS just right after calling switch_to_runtime_mapping.
So we can add more prints in remove_identity_mapping() and 
remove_temporary_mapping().
I will have a look to update this patch.

Cheers,

--
Julien Grall