[PATCH] efi_loader: support EFI_OS_INDICATIONS_BOOT_TO_FW_UI

[Simon Glass]

Hi Gary,

On Fri, 3 Apr 2026 at 09:41, Gary Guo <gary at garyguo.net> wrote:
>
> On Fri Apr 3, 2026 at 2:22 PM BST, Simon Glass wrote:
> > Hi Gary,
> >
> > On 2026-03-31T19:18:51, Gary Guo <gary at garyguo.net> wrote:
> >> efi_loader: support EFI_OS_INDICATIONS_BOOT_TO_FW_UI
> >>
> >> EFI variable OsIndications have a bit EFI_OS_INDICATIONS_BOOT_TO_FW_UI
> >> indicating that the OS (or next stage bootloader) requests booting into
> >> firmware UI instead of continuing autoboot process.
> >>
> >> Support it by having autoboot.c asking EFI bootmgr if boot should continue,
> >> which checks and clear the bit (so the next boot continue as normal).
> >>
> >> With this change, systemd-boot will show a "Reboot Into Firmware Interface"
> >> option which will be able to drop back to u-boot. This can be useful if
> >> bootdelay is configured to be -2.
> >>
> >> Signed-off-by: Gary Guo <gary at garyguo.net>
> >
> >> diff --git a/lib/efi_loader/efi_bootmgr.c b/lib/efi_loader/efi_bootmgr.c
> >> @@ -1290,6 +1290,51 @@ out:
> >> +bool efi_should_abort_autoboot(void)
> >> +{
> >> +     efi_status_t ret;
> >> +     u64 os_indications = 0x0;
> >> +     efi_uintn_t size;
> >> +     efi_status_t r;
> >
> > (I'm leaving the proper review to Ilias & Heinrich, this is just a few
> > nits and a though)
> >
> > Please can you use a single variable name for both efi_status_t variables.
>
> Ah, I think I copied the init part from somewhere else and forget to merge the
> variable names.
>
> I'll adjust the variable name in the next version after receiving more reviews.
>
> >
> >> +     ret = efi_init_obj_list();
> >> +     if (ret != EFI_SUCCESS) {
> >> +             log_err("Error: Cannot initialize UEFI sub-system, r = %lu\n",
> >> +                     ret & ~EFI_ERROR_MASK);
> >
> > The log message says "r = " but prints ret. The similar message in
> > efi_bootmgr_run() just prints the value without a prefix.
>
> Sorry, what do you mean by "without a prefix"? I think the code is identical to
> the one in `efi_bootmgr_run`?

I mean you don't need r = in the message. You could say (err %lu) perhaps?

>
> >
> > I would also like to see the code which adjusts the variable placed in
> > a function.
>
> You mean the bit clearing part? What benefit does that provide, considering that
> this is just a single function call?

There is reading and write. Being able to control that could end up in
a command at some point. It is a useful feature. Up to you though.

Regards,
Simon