The rtc-efi driver declares that the EFI 'epoch' is 1/1/1998, but the UEFI spec does not define it at all. It does define a minimum of 1900 for the 'Year' member of the EFI_TIME struct, so let's use 1900 as the minimum year and not 1998. This prevents rtc_read_time() failures when the RTC that backs the EFI time services is set to a date before 1998. Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx> Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx> Cc: rtc-linux@xxxxxxxxxxxxxxxx Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> --- drivers/rtc/rtc-efi.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/rtc/rtc-efi.c b/drivers/rtc/rtc-efi.c index cb989cd00b14..4a93b0bbf22c 100644 --- a/drivers/rtc/rtc-efi.c +++ b/drivers/rtc/rtc-efi.c @@ -25,9 +25,12 @@ #define EFI_ISDST (EFI_TIME_ADJUST_DAYLIGHT|EFI_TIME_IN_DAYLIGHT) /* - * EFI Epoch is 1/1/1998 + * The UEFI spec does not literally define an epoch, but it does + * define EFI_TIME::Year as having a value between 1900 and 9999. + * (UEFI spec v2.5 paragraph 7.3) + * So let's use 1900 as the EFI epoch year. */ -#define EFI_RTC_EPOCH 1998 +#define EFI_RTC_EPOCH 1900 /* * returns day of the year [0-365] @@ -40,8 +43,6 @@ compute_yday(efi_time_t *eft) } /* * returns day of the week [0-6] 0=Sunday - * - * Don't try to provide a year that's before 1998, please ! */ static int compute_wday(efi_time_t *eft) @@ -60,9 +61,9 @@ compute_wday(efi_time_t *eft) ndays += compute_yday(eft); /* - * 4=1/1/1998 was a Thursday + * 1=1/1/1900 was a Monday */ - return (ndays + 4) % 7; + return (ndays + 1) % 7; } static void -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
