For debugging purposes, allow the runtime override mask to be set from a
EFI variable if one exists. For instance, the RT supported mask can be
set to 0xfffd to disable the SetTime() runtime service, and enable all
others:
echo -ne "\x7\0\0\0\xfd\xff" \
> /sys/firmware/efi/efivars/LinuxRtMaskOverride-eb66918a-7eef-402a-842e-931d21c38ae9
Signed-off-by: Ard Biesheuvel <ardb@xxxxxxxxxx>
---
drivers/firmware/efi/efi.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index a46df5d1d0942751..faed1ef78c044924 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -367,7 +367,17 @@ static int __init efisubsys_init(void)
}
}
- if (efi_rt_services_supported(EFI_RT_SUPPORTED_TIME_SERVICES))
+ if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE)) {
+ unsigned long size = sizeof(efi.runtime_supported_mask);
+
+ if (efi.get_variable(L"LinuxRtMaskOverride",
+ &EFI_RT_PROPERTIES_TABLE_GUID, NULL, &size,
+ &efi.runtime_supported_mask) == EFI_SUCCESS)
+ pr_info("Overriding runtime_supported_mask to 0x%x\n",
+ efi.runtime_supported_mask);
+ }
+
+ if (efi_rt_services_supported(EFI_RT_SUPPORTED_GET_TIME))
platform_device_register_simple("rtc-efi", 0, NULL, 0);
/* We register the efi directory at /sys/firmware/efi */
--
2.35.1
