Hi Heinrich,
On Tue, 17 Oct 2023 at 11:55, Heinrich Schuchardt < heinrich.schuchardt@canonical.com> wrote:
Forward and backward compatibility of Linux kernel device-trees is sometimes missing. One solution approach is to load a kernel specific device-tree. This can either be done via a U-Boot scripts (like the one generated by Debian package flash-kernel or by a boot loader like GRUB. The boot loader approach currently requires to know the device-tree name before first boot which makes it unusable for generic images.
Expose the device-tree file name as EFI variable FdtFile. This will allow bootloaders to load a kernel specific device-tree.
Signed-off-by: Heinrich Schuchardt heinrich.schuchardt@canonical.com
lib/efi_loader/efi_setup.c | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+)
diff --git a/lib/efi_loader/efi_setup.c b/lib/efi_loader/efi_setup.c index e6de685e87..b24feb94dc 100644 --- a/lib/efi_loader/efi_setup.c +++ b/lib/efi_loader/efi_setup.c @@ -26,6 +26,27 @@ void __weak allow_unaligned(void) { }
+/**
- efi_init_fdtfile() - set EFI variable FdtFile
- Return: status code
- */
+static efi_status_t efi_init_fdtfile(void) +{
char *val;val = env_get("fdtfile");if (!val)return EFI_SUCCESS;return efi_set_variable_int(u"FdtFile",&efi_u_boot_guid,EFI_VARIABLE_BOOTSERVICE_ACCESS |EFI_VARIABLE_RUNTIME_ACCESS |
Why is runtime access needed? Wouldn't the choice be done before ExitBootServices?
[...]
Thanks /Ilias