[PATCH 1/5] x86: fsp: Allow skipping init code when chain loading

[Simon Glass]

Hi Bin,

On Mon, 3 Feb 2020 at 04:05, Bin Meng <bmeng.cn at gmail.com> wrote:
>
> Hi Simon,
>
> On Sun, Dec 22, 2019 at 12:13 AM Simon Glass <sjg at chromium.org> wrote:
> >
> > When U-Boot is no the first-stage bootloader much of this code is not
> > needed and can break booting. Add checks for this to the FSP code.
> >
> > Rather than checking for the amount of available SDRAM, just use 1GB in
> > this situation, which should be safe. Using 2GB may run into a memory
> > hole on some SoCs.
> >
> > Signed-off-by: Simon Glass <sjg at chromium.org>
> > ---
> >
> >  arch/x86/lib/fsp/fsp_dram.c     |  8 ++++++++
> >  arch/x86/lib/fsp/fsp_graphics.c |  3 +++
> >  arch/x86/lib/fsp2/fsp_dram.c    | 10 ++++++++++
> >  arch/x86/lib/fsp2/fsp_init.c    |  2 +-
> >  4 files changed, 22 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/x86/lib/fsp/fsp_dram.c b/arch/x86/lib/fsp/fsp_dram.c
> > index 9ce0ddf0d3..15e82de2fe 100644
> > --- a/arch/x86/lib/fsp/fsp_dram.c
> > +++ b/arch/x86/lib/fsp/fsp_dram.c
> > @@ -44,6 +44,14 @@ int dram_init_banksize(void)
> >         phys_addr_t low_end;
> >         uint bank;
> >
> > +       if (!ll_boot_init()) {
> > +               gd->bd->bi_dram[0].start = 0;
> > +               gd->bd->bi_dram[0].size = gd->ram_size;
> > +
> > +               mtrr_add_request(MTRR_TYPE_WRBACK, 0, gd->ram_size);
> > +               return 0;
> > +       }
> > +
>
> I wonder why this change is needed. When booting from other
> bootloader, this dram_init_banksize() will not be called, no?

How about this:

It is useful to be able to boot the same x86 image on a device with or
without a first-stage bootloader. For example, with chromebook_coral, it
is helpful for testing to be able to boot the same U-Boot (complete with
FSP) on bare metal and from coreboot. It allows checking of things like
CPU speed, comparing registers, ACPI tables and the like.

The idea is to change ll_boot_init() to false, and rebuild without changing
anything else.

Regards,
Simon