diff options
Diffstat (limited to 'src/interface')
| -rw-r--r-- | src/interface/linux/linux_timer.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/src/interface/linux/linux_timer.c b/src/interface/linux/linux_timer.c index bf55cd188..7a994517b 100644 --- a/src/interface/linux/linux_timer.c +++ b/src/interface/linux/linux_timer.c @@ -55,6 +55,12 @@ static unsigned long linux_ticks_per_sec(void) * linux doesn't provide an easy access to jiffies so implement it by measuring * the time since the first call to this function. * + * Since this function is used to seed the (non-cryptographic) random + * number generator, we round the start time down to the nearest whole + * second. This minimises the chances of generating identical RNG + * sequences (and hence identical TCP port numbers, etc) on + * consecutive invocations of iPXE. + * * @ret ticks Current time, in ticks */ static unsigned long linux_currticks(void) @@ -71,7 +77,7 @@ static unsigned long linux_currticks(void) linux_gettimeofday(&now, NULL); unsigned long ticks = (now.tv_sec - start.tv_sec) * linux_ticks_per_sec(); - ticks += (now.tv_usec - start.tv_usec) / (long)(1000000 / linux_ticks_per_sec()); + ticks += now.tv_usec / (long)(1000000 / linux_ticks_per_sec()); return ticks; } |