Revert "hwclock-rtc.c: try the 'new' rtc class first"

This (effectively) reverts commit
1811900a91be856e794005511eac7859adb8e383.

There was no real motivation given, and it certainly makes the default
behaviour of hwclock on current linux systems counter-intuitive: udev
has a standard rule so that whichever rtc device is designated as the
CONFIG_RTC_HCTOSYS_DEVICE one in the kernel configuration also becomes
the target of the /dev/rtc symlink. People may have some other way of
setting that symlink, but regardless, that must be considered the
primary or default rtc for the system.

Also, busybox's implementation of hwclock still uses the original
/dev/rtc, /dev/rtc0 order, meaning that installing util-linux's
version on a board previously using busybox leads to unexpected
regressions - it's not at all clear that one must go around and stick
--rtc /dev/rtc on every hwclock invocation in all scripts.

While it's usually busybox that should align with the full-fledged
implementation, in this case, I do believe that util-linux is
wrong.

There is no change in behaviour on systems that for some reason do not
have a /dev/rtc symlink, or for which it is a symlink to rtc0 (such as
on any board with only a single RTC device). However, I do understand
that reverting this after 8 years can itself lead to regressions, and
I can understand if it would be rejected for that reason. However, in
that case I'd appreciate a config option so that one can choose the
primary rtc device at build time.

diff --git a/include/pathnames.h b/include/pathnames.h
index a30194b109be2e8c213bc42d2e15bf872ab79a21..c14605f6678ee3b1647bf5886bdfad4e81acee49 100644 (file)
--- a/include/pathnames.h
+++ b/include/pathnames.h
@@ -176,7 +176,7 @@
 #ifdef __ia64__
 # define _PATH_RTC_DEV         "/dev/efirtc"
 #else
-# define _PATH_RTC_DEV         "/dev/rtc0"
+# define _PATH_RTC_DEV         "/dev/rtc"
 #endif
 
 /* raw paths*/

diff --git a/sys-utils/hwclock-rtc.c b/sys-utils/hwclock-rtc.c
index e1ee6a05d13d78cfcd34c56a771f77e12d064378..1fb042e329bfcde6f0a6603bafb99442508ece61 100644 (file)
--- a/sys-utils/hwclock-rtc.c
+++ b/sys-utils/hwclock-rtc.c
@@ -94,8 +94,8 @@ static int open_rtc(const struct hwclock_control *ctl)
                "/dev/efirtc",
                "/dev/misc/efirtc",
 #endif
-               "/dev/rtc0",
                "/dev/rtc",
+               "/dev/rtc0",
                "/dev/misc/rtc"
        };
        size_t i;

diff --git a/sys-utils/hwclock.8.adoc b/sys-utils/hwclock.8.adoc
index 0b23a37e8dae666f16d352a3cbbf73ac0cac0cb9..350d502759565f3a1642de96504f5339884ca240 100644 (file)
--- a/sys-utils/hwclock.8.adoc
+++ b/sys-utils/hwclock.8.adoc
@@ -137,7 +137,7 @@ This option is meaningful for ISA compatible machines in the x86 and x86_64 fami
 This option is required when using the *--setepoch* function. The minimum _year_ value is 1900. The maximum is system dependent (*ULONG_MAX - 1*).
 
 *-f*, **--rtc=**__filename__::
-Override *hwclock*'s default rtc device file name. Otherwise it will use the first one found in this order: _/dev/rtc0_, _/dev/rtc_, _/dev/misc/rtc_. For *IA-64:* _/dev/efirtc_ _/dev/misc/efirtc_
+Override *hwclock*'s default rtc device file name. Otherwise it will use the first one found in this order: _/dev/rtc_, _/dev/rtc0_, _/dev/misc/rtc_. For *IA-64:* _/dev/efirtc_ _/dev/misc/efirtc_
 
 *-l*, *--localtime*; *-u*, *--utc*::
 Indicate which timescale the Hardware Clock is set to.
@@ -373,7 +373,7 @@ The system timezone file.
 _/usr/share/zoneinfo/_::
 The system timezone database directory.
 
-Device files *hwclock* may try for Hardware Clock access: _/dev/rtc0_ _/dev/rtc_ _/dev/misc/rtc_ _/dev/efirtc_ _/dev/misc/efirtc_
+Device files *hwclock* may try for Hardware Clock access: _/dev/rtc_ _/dev/rtc0_ _/dev/misc/rtc_ _/dev/efirtc_ _/dev/misc/efirtc_
 
 == SEE ALSO