[PATCH] riscv/start: Startup sequence update.

[Hesham Almatary]

On Thu, 29 Apr 2021 at 20:07, Gedare Bloom <gedare at rtems.org> wrote:
>
> On Thu, Apr 29, 2021 at 11:53 AM Sebastian Huber
> <sebastian.huber at embedded-brains.de> wrote:
> >
> >
> > On 28/04/2021 15:55, Somesh Deshmukh wrote:
> > > +/* Clear .bss */
> > > +LADDR        a0, bsp_section_bss_begin
> > > +li   a1, 0
> > > +LADDR        a2, bsp_section_bss_size
> > > +call memset
> > > +
> > >   #ifdef BSP_START_COPY_FDT_FROM_U_BOOT
> > >       mv      a0, a1
> > >       call    bsp_fdt_copy
> > >   #endif
> >
> > How did you test this? The above memset() sets register a1 to 0 and
> > probably uses this register also, the a1 is later used for the
> > bsp_fdt_copy(), probably with an invalid value.
> >
> Good point, that a1 I guess is a parameter passed in by uboot and
> needs to be preserved if this code should keep working.
>
Right. a1 will be zero on the  bsp_fdt_copy() call this way.

> > I would place the device tree in a noinit section.
> >
> That is probably a better solution.
>
> It should also be documented in this start.S file what are the
> assumptions about parameters coming from the bootloader since it is
> not obvious.
+1
>
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