If our tests don't cover this case, we probably should.
Subject: [chrony-dev] [PATCH] macOS 11.0 (Big Sur) beta - Bug in
implementation of ntp_adjtime()
From: Bryan Christianson <br...@whatroute.net>
Date: Sun, 30 Aug 2020 09:49:22 +1200
To: chrony-...@chrony.tuxfamily.org
Cc: Bryan Christianson <br...@whatroute.net>
macOS 11.0 (Big Sur) beta incorrectly returns timex.freq as an unsigned
number. This patch is a workaround for the bug and should be removed when
Apple fix the problem (assuming they will). The patch also extends the
ntpadjtime test to cover negative frequencies.
---
sys_timex.c | 23 +++++++++++++++++++++--
test/kernel/ntpadjtime.c | 2 +-
2 files changed, 22 insertions(+), 3 deletions(-)
diff --git a/sys_timex.c b/sys_timex.c
index 0a6b438..aa1508a 100644
--- a/sys_timex.c
+++ b/sys_timex.c
@@ -68,6 +68,25 @@ static int sys_tai_offset;
/* ================================================== */
+static inline double
+txc_freq(const struct timex *txc)
+{
+ double freq_ppm;
+
+ freq_ppm = txc->freq / FREQ_SCALE;
+
+#ifdef MACOSX
+ /* temporary work-around for Apple bug treating freq as unsigned number */
+ if (freq_ppm > 32767) {
+ freq_ppm -= 65536;
+ }
+#endif
+
+ return -freq_ppm;
+}
+
+/* ================================================== */
+
static double
read_frequency(void)
{
@@ -77,7 +96,7 @@ read_frequency(void)
SYS_Timex_Adjust(&txc, 0);
- return txc.freq / -FREQ_SCALE;
+ return txc_freq(&txc);
}
/* ================================================== */
@@ -92,7 +111,7 @@ set_frequency(double freq_ppm)
SYS_Timex_Adjust(&txc, 0);
- return txc.freq / -FREQ_SCALE;
+ return txc_freq(&txc);
}
/* ================================================== */
diff --git a/test/kernel/ntpadjtime.c b/test/kernel/ntpadjtime.c
index d6be154..96c069f 100644
--- a/test/kernel/ntpadjtime.c
+++ b/test/kernel/ntpadjtime.c
@@ -52,7 +52,7 @@ test_freqrange(void)
printf("freq range:\n");
- for (i = 0; i <= 1000; i += 50) {
+ for (i = -1000; i <= 1000; i += 50) {
t.modes = MOD_FREQUENCY;
t.freq = i << 16;
printf("%4d ppm => ", i);
--
2.24.3 (Apple Git-128)
--
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