diff options
Diffstat (limited to 'firmware/include/vboot_api.h')
| -rw-r--r-- | firmware/include/vboot_api.h | 16 |
1 files changed, 5 insertions, 11 deletions
diff --git a/firmware/include/vboot_api.h b/firmware/include/vboot_api.h index cedf266d..c71dfbf1 100644 --- a/firmware/include/vboot_api.h +++ b/firmware/include/vboot_api.h @@ -457,18 +457,12 @@ void VbExDebug(const char *format, ...) /* Timer and delay (first two from utility.h) */ /** - * Read a high-resolution timer. Returns the current timer value in arbitrary - * units. + * Read a microsecond timer. * - * This is intended for benchmarking, so this call MUST be fast. The timer - * frequency must be >1 KHz (preferably >1 MHz), and the timer must not wrap - * around for at least 10 minutes. It is preferable (but not required) that - * the timer be initialized to 0 at boot. - * - * It is assumed that the firmware has some other way of communicating the - * timer frequency to the OS. For example, on x86 we use TSC, and the OS - * kernel reports the initial TSC value at kernel-start and calculates the - * frequency. */ + * This should have a sufficient number of bits to avoid wraparound for at + * least 10 minutes. A 32-bit value would be plenty, but for historical + * reasons this returns uint64_t. + */ uint64_t VbExGetTimer(void); /** |