[U-Boot] [PATCH v2 1/2] x86: Add efi runtime reset

[Simon Glass]

Hi Alex,

On Mon, 28 Jan 2019 at 12:27, Alexander Graf <agraf at suse.de> wrote:
>
>
>
> On 28.01.19 20:24, Simon Glass wrote:
> > Hi Alex,
> >
> > On Mon, 28 Jan 2019 at 12:15, Alexander Graf <agraf at suse.de> wrote:
> >>
> >>
> >>
> >> On 28.01.19 20:13, Simon Glass wrote:
> >>> Hi,
> >>>
> >>> On Mon, 28 Jan 2019 at 08:42, Alexander Graf <agraf at suse.de> wrote:
> >>>>
> >>>> Our selftest will soon test the actual runtime reset function rather than
> >>>> the boot time one. For this, we need to ensure that the runtime version
> >>>> actually succeeds on x86 to keep our travis tests work.
> >>>>
> >>>> So this patch implements an x86 runtime reset function. It is missing
> >>>> shutdown functionality today, but OSs usually implement that via ACPI
> >>>> and this function does more than the stub from before, so it's at least
> >>>> an improvement.
> >>>>
> >>>> Signed-off-by: Alexander Graf <agraf at suse.de>
> >>>> ---
> >>>>  drivers/sysreset/sysreset_x86.c | 23 +++++++++++++++++++++++
> >>>>  1 file changed, 23 insertions(+)
> >>>>
> >>>> diff --git a/drivers/sysreset/sysreset_x86.c b/drivers/sysreset/sysreset_x86.c
> >>>> index 20b958cfd4..efed45ccb7 100644
> >>>> --- a/drivers/sysreset/sysreset_x86.c
> >>>> +++ b/drivers/sysreset/sysreset_x86.c
> >>>> @@ -10,6 +10,29 @@
> >>>>  #include <sysreset.h>
> >>>>  #include <asm/io.h>
> >>>>  #include <asm/processor.h>
> >>>> +#include <efi_loader.h>
> >>>> +
> >>>> +#ifdef CONFIG_EFI_LOADER
> >>>> +void __efi_runtime EFIAPI efi_reset_system(
> >>>> +                       enum efi_reset_type reset_type,
> >>>> +                       efi_status_t reset_status,
> >>>> +                       unsigned long data_size, void *reset_data)
> >>>> +{
> >>>> +       u32 value = 0;
> >>>> +
> >>>> +       if (reset_type == EFI_RESET_COLD)
> >>>> +               value = SYS_RST | RST_CPU | FULL_RST;
> >>>> +       else if (reset_type == EFI_RESET_WARM)
> >>>> +               value = SYS_RST | RST_CPU;
> >>>
> >>> The EFI should use the sysreset driver and sysreset_walk() or similar,
> >>> rather than having a function called directly.
> >>
> >> It can't. At this point all of DM is long gone. We're in runtime space here.
> >
> > This has come up before. We'll end up with a lot of duplication if we
> > cannot solve this. I think the run-time code will need to be built and
> > linked separately so that all necessary code is pulled in.
>
> It's mostly a question of size. We can even transform all of U-Boot into
> huge runtime services if we keep the relocation tables around and apply
> relocations manually for everything.
>
> The problem is that if we do that, we'll become even bigger than we are
> now, no?

I did a change to build U-Boot as a library, perhaps it could build on
that. The 'run-time U-Boot' won't be any bigger than the code that is
actually used. Also I don't think memory usage is a concern in systems
that use UEFI :-)

The problem with the current approach is that everything becomes
parallel to DM, duplicating existing code, and that is complicated
too.

Regards,
Simon