Am 16. Februar 2026 08:24:19 MEZ schrieb Michal Simek <[email protected]>: > > >On 2/15/26 09:48, Heinrich Schuchardt wrote: >> On 2/11/26 16:56, Michal Simek wrote: >>> From: Shantur Rathore <[email protected]> >>> >>> Currently U-Boot uses ESP as storage for EFI variables. >>> Devices with SPI Flash are used for storing environment with this >>> commit we allow EFI variables to be stored on SPI Flash. >>> >>> https://github.com/rhboot/efivar >>> is not updated to support this location that's why you can mimic it by >>> running: >>> dd >>> if=/sys/firmware/efi/efivars/VarToFile-b2ac5fc9-92b7-4acd-aeac-11e818c3130c >>> \ >>> of=/tmp/vars skip=4 bs=1 >>> flashcp /tmp/vars /dev/mtdX >>> >>> where mtdX should match location defined by >>> CONFIG_EFI_VARIABLE_SF_OFFSET/CONFIG_EFI_VAR_BUF_SIZE. >>> >>> Signed-off-by: Shantur Rathore <[email protected]> >>> Signed-off-by: Michal Simek <[email protected]> >>> Tested-by: Neil Armstrong <[email protected]> # on AML-S905D3-CC >>> Acked-by: Ilias Apalodimas <[email protected]> >>> >>> --- >>> >>> Changes in v8: >>> - Add missing EFI_VARIABLE_SF_STORE dependency to >>> EFI_VARIABLE_SF_DEVICE_INDEX >>> >>> Changes in v7: >>> - sed -i 's/efi_var_from/efi_var_from_storage/g' >>> >>> Changes in v6: >>> - sed -i 's/efi_var_read/efi_var_from/g' >>> - sed -i 's/efi_var_write/efi_var_to_storage/g' >>> >>> Changes in v4: >>> - Extend Kconfig description >>> - Extend commit message and describe efivar missing part >>> - use unify methods for reading/writing variable >>> >>> Changes in v3: >>> - Fixed compiler warnings. >>> >>> Changes in v2: >>> - Refactored efi_var_file to move common parts out as requested >>> - Changed ifdefs to use CONFIG_IS_DEFINED >>> - Fixed typos >>> >>> lib/efi_loader/Kconfig | 35 +++++++++++++- >>> lib/efi_loader/Makefile | 1 + >>> lib/efi_loader/efi_var_sf.c | 92 +++++++++++++++++++++++++++++++++++++ >>> 3 files changed, 127 insertions(+), 1 deletion(-) >>> create mode 100644 lib/efi_loader/efi_var_sf.c >>> >>> diff --git a/lib/efi_loader/Kconfig b/lib/efi_loader/Kconfig >>> index 579eed658801..0f6f927ddaf1 100644 >>> --- a/lib/efi_loader/Kconfig >>> +++ b/lib/efi_loader/Kconfig >>> @@ -124,6 +124,24 @@ config EFI_VARIABLE_FILE_STORE >>> Select this option if you want non-volatile UEFI variables to be >>> stored as file /ubootefi.var on the EFI system partition. >>> +config EFI_VARIABLE_SF_STORE >>> + bool "Store non-volatile UEFI variables in SPI Flash" >>> + depends on SPI_FLASH >>> + help >>> + Select this option if you want non-volatile UEFI variables to be >>> + stored in SPI Flash. >>> + >>> + Define CONFIG_EFI_VARIABLE_SF_OFFSET as offset in SPI Flash to use as >>> + the storage for variables. CONFIG_EFI_VAR_BUF_SIZE defines the space >>> + needed. >>> + >>> + Note that SPI Flash devices have a limited number of program/erase >>> + cycles. Frequent updates to UEFI variables may cause excessive wear >>> + and can permanently damage the flash device, particularly on SPI NAND >>> + or low-end SPI NOR parts without wear leveling. This option should be >>> + used with care on such systems, and is not recommended for platforms >>> + where UEFI variables are updated frequently. >>> + >>> config EFI_MM_COMM_TEE >>> bool "UEFI variables storage service via the trusted world" >>> depends on OPTEE >>> @@ -153,7 +171,7 @@ endchoice >>> config EFI_RT_VOLATILE_STORE >>> bool "Allow variable runtime services in volatile storage (e.g RAM)" >>> - depends on EFI_VARIABLE_FILE_STORE >>> + depends on EFI_VARIABLE_FILE_STORE || EFI_VARIABLE_SF_STORE >> >> Hello Michal, >> >> If the backend store is SPI flash, we should not publish the variable >> "RTStorageVolatile" at runtime as currently defined. >> >> For the background see this commit for the efivar library: >> >> https://github.com/rhboot/efivar/commit/68daa04654acbe1bbaa17ebfc23c371b39e69c6b >> >> The first three patches look correct to me and I will add them to a merge >> request for efi-next. > >Do I read it that when I don't allow to select EFI_RT_VOLATILE_STORE you will >be fine with the patch itself?
This was my only concern. Maybe setting the file name to /dev/mtd/by-name/<partition name> would work with efivar. But I have not tested it. In U-Boot we could replace EFI_VARIABLE_SF_DEVICE_INDEX, SIZE, and OFFSET by a partition name, too. That way it would be the common device-tree for U-Boot and Linux controlling the placement of the variables store. > > >> The usage of efi_var_mem_ins() and efi_var_mem_del() when SetVariable() does >> not change anything is not flash-friendly. Michal, do you want to have a >> look at this area? > >That's known limitation describe in EFI_VARIABLE_SF_STORE Kconfig Note. This could be a topic for future work. Best regards Heinrich
