Re: [Xen-devel] [PATCH 06/17] xen/arm64: head: Introduce distinct paths for the boot CPU and secondary CPUs

[Julien Grall <julien.grall@xxxxxxx>]

Hi Stefano,

On 26/06/2019 02:00, Stefano Stabellini wrote:
> On Mon, 10 Jun 2019, Julien Grall wrote:
> > The boot code is currently quite difficult to go through because of the
> > lack of documentation and a number of indirection to avoid executing
> > some path in either the boot CPU or secondary CPUs.
> >
> > In an attempt to make the boot code easier to follow, each parts of the
> > boot are now in separate functions. Furthermore, the paths for the boot
> > CPU and secondary CPUs are now distincted and for now will call each
I notice a few typo in my commit message:

s/distincted/distinct/

> > functions.
> >
> > Follow-ups will remove unecessary calls and do further improvement
s/unecessary/unnecessary/

> > +launch:
> >           PRINT("- Ready -\r\n")
> >   
> >           /* The boot CPU should go straight into C now */
> > @@ -594,7 +635,6 @@ paging:
> >           dsb   sy                     /* Ensure completion of TLB flush */
> >           isb
> >   
> > -launch:
> Just below PRINT("- Ready -\r\n"), there is still a:
>
>    cbz   x22, launch
>
> moving the launch label up it looks like it will cause an infinite loop?
Urgh. this line is dropped in a later patch, so the issue only would happen 
during bisection.
I will update the code to avoid the infinite loop here.

> Everything else looks good, and I like the reorg of the code.
Thank you! I will rework the arm32 code the same way then :).

> >           ldr   x0, =init_data
> >           add   x0, x0, #INITINFO_stack /* Find the boot-time stack */
> >           ldr   x0, [x0]
> > @@ -609,6 +649,7 @@ launch:
> >           b     start_xen              /* and disappear into the land of C */
> >   1:
> >           b     start_secondary        /* (to the appropriate entry point) */
> > +ENDPROC(launch)
Cheers,

--
Julien Grall

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