Hi Mark,
On Wed, 7 Jan 2026 at 12:38, Mark Kettenis <[email protected]> wrote:
>
> > From: Simon Glass <[email protected]>
> > Date: Wed, 7 Jan 2026 12:02:27 -0700
> >
> > On Tue, 6 Jan 2026 at 19:42, Peter Robinson <[email protected]> wrote:
> > >
> > > On Wed, 7 Jan 2026 at 00:33, Simon Glass <[email protected]> wrote:
> > > >
> > > > From: Simon Glass <[email protected]>
> > > >
> > > > This work-around dates from 2019 and grub 2.04 which is quite old. New
> > > > builds of grub don't have the problem and old boards presumably use an
> > > > older U-Boot, so don't need this.
> > > >
> > > > Drop it.
> > > >
> > > > Signed-off-by: Simon Glass <[email protected]>
> > > > Signed-off-by: Simon Glass <[email protected]>
> > > > ---
> > > >
> > > > configs/mt7623n_bpir2_defconfig | 1 -
> > > > lib/efi_loader/Kconfig | 10 ----------
> > > > lib/efi_loader/efi_boottime.c | 26 --------------------------
> > > > 3 files changed, 37 deletions(-)
> > > >
> > > > diff --git a/configs/mt7623n_bpir2_defconfig
> > > > b/configs/mt7623n_bpir2_defconfig
> > > > index 404380558f2..d75168a72ed 100644
> > > > --- a/configs/mt7623n_bpir2_defconfig
> > > > +++ b/configs/mt7623n_bpir2_defconfig
> > > > @@ -13,7 +13,6 @@ CONFIG_DEFAULT_DEVICE_TREE="mt7623n-bananapi-bpi-r2"
> > > > CONFIG_TARGET_MT7623=y
> > > > CONFIG_SYS_BOOTM_LEN=0x4000000
> > > > CONFIG_SYS_LOAD_ADDR=0x84000000
> > > > -# CONFIG_EFI_GRUB_ARM32_WORKAROUND is not set
> > > > CONFIG_FIT=y
> > > > CONFIG_FIT_VERBOSE=y
> > > > CONFIG_DISTRO_DEFAULTS=y
> > > > diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig
> > > > index 13e44be1d06..5585c841c27 100644
> > > > --- a/lib/efi_loader/Kconfig
> > > > +++ b/lib/efi_loader/Kconfig
> > > > @@ -505,16 +505,6 @@ config EFI_LOADER_BOUNCE_BUFFER
> > > > hardware we can create a bounce buffer so that payloads don't
> > > > have to
> > > > worry about platform details.
> > > >
> > > > -config EFI_GRUB_ARM32_WORKAROUND
> > > > - bool "Workaround for GRUB on 32bit ARM"
> > > > - default n if ARCH_BCM283X || ARCH_SUNXI || ARCH_QEMU
> > > > - default y
> > > > - depends on ARM && !ARM64
> > > > - help
> > > > - GRUB prior to version 2.04 requires U-Boot to disable caches.
> > > > This
> > > > - workaround currently is also needed on systems with caches
> > > > that
> > > > - cannot be managed via CP15.
> > >
> > > This also states that it's needed for systems that can't be managed by
> > > CP15, what systems are they, how are those platforms addressed?
> >
> > I'm guessing that some systems have level2 caches with their own
> > software interface. I certainly have seen this with Tegra2/3, for
> > example.
>
> This is already being discussed in another thread on the mailing list
> started by Jan Kiszka:
>
> https://lists.denx.de/pipermail/u-boot/2026-January/606817.html
>
> My suggestion would be to drop this patch from your set and let that
> thread run its course.
Yes I did see that and I was pleased to see that someone else was
interested in this topic.
Still, that thread does not actually include a patch. So let's see how
it pans out.
>
> > >
> > > > config EFI_ESRT
> > > > bool "Enable the UEFI ESRT generation"
> > > > depends on EFI_CAPSULE_FIRMWARE_MANAGEMENT
> > > > diff --git a/lib/efi_loader/efi_boottime.c
> > > > b/lib/efi_loader/efi_boottime.c
> > > > index 0bc66ee61a8..c31ee53cde6 100644
> > > > --- a/lib/efi_loader/efi_boottime.c
> > > > +++ b/lib/efi_loader/efi_boottime.c
> > > > @@ -2139,29 +2139,6 @@ error:
> > > > return EFI_EXIT(ret);
> > > > }
> > > >
> > > > -/**
> > > > - * efi_exit_caches() - fix up caches for EFI payloads if necessary
> > > > - */
> > > > -static void efi_exit_caches(void)
> > > > -{
> > > > -#if defined(CONFIG_EFI_GRUB_ARM32_WORKAROUND)
> > > > - /*
> > > > - * Boooting Linux via GRUB prior to version 2.04 fails on 32bit
> > > > ARM if
> > > > - * caches are enabled.
> > > > - *
> > > > - * TODO:
> > > > - * According to the UEFI spec caches that can be managed via
> > > > CP15
> > > > - * operations should be enabled. Caches requiring platform
> > > > information
> > > > - * to manage should be disabled. This should not happen in
> > > > - * ExitBootServices() but before invoking any UEFI binary is
> > > > invoked.
> > > > - *
> > > > - * We want to keep the current workaround while GRUB prior to
> > > > version
> > > > - * 2.04 is still in use.
> > > > - */
> > > > - cleanup_before_linux();
> > > > -#endif
> > > > -}
> > > > -
> > > > /**
> > > > * efi_exit_boot_services() - stop all boot services
> > > > * @image_handle: handle of the loaded image
> > > > @@ -2245,9 +2222,6 @@ static efi_status_t EFIAPI
> > > > efi_exit_boot_services(efi_handle_t image_handle,
> > > > /* Patch out unsupported runtime function */
> > > > efi_runtime_detach();
> > > >
> > > > - /* Fix up caches for EFI payloads if necessary */
> > > > - efi_exit_caches();
> > > > -
> > > > /* Disable boot time services */
> > > > systab.con_in_handle = NULL;
> > > > systab.con_in = NULL;
> > > > --
> > > > 2.43.0
> > > >
> >
Regards,
Simon
