hwclock --directisa in /etc/rc.d/rc.S

Speek · 07-23-2012, 05:52 AM

This is from /etc/rc.d/rc.S:

Code:

# Check for a broken motherboard RTC clock (where ioports for rtc are
# unknown) to prevent hwclock causing a hang:
if ! grep -q -w rtc /proc/ioports ; then
  CLOCK_OPT="--directisa"
fi

In my PC the RTC device is named rtc0:

Code:

$ grep rtc /proc/ioports 
  0070-0071 : rtc0

So the --directisa option is passed to hwclock (while it should not).

From reading the hwclock manpage I think the --directisa option is not needed anymore in the current version:

Code:

--directisa
              This option is meaningful only on an ISA machine or an  Alpha  (which  implements
              enough  of  ISA  to be, roughly speaking, an ISA machine for hwclock's purposes).
              For other machines, it has no effect.  This option tells hwclock to use  explicit
              I/O instructions to access the Hardware Clock.  Without this option, hwclock will
              try to use the /dev/rtc device (which it assumes to be driven by the  RTC  device
              driver).   If  it  is  unable  to  open the device (for reading), it will use the
              explicit I/O instructions anyway.

But if you think the test should stay I suggest to change it to something like this:

Code:

grep -qw 'rtc0\?' /proc/ioports

volkerdi · 07-23-2012, 11:19 PM

I've been burned by removing old workarounds in the past. Looks like this one was added in 2004 by Piter Punk, well past the ISA era, and likely fixed something then. I don't have specific notes about what we were trying to find in /proc/ioports, but rtc0 (or rtc*) could well have been what we were trying to match. The nature of voodoo workarounds (especially for borken hardware) tends to be that something fixes a bug, but does not always make logical sense. As the man page says states that this option "has no effect" on non-ISA machines I'd consider it harmless unless you can tell me that it's causing problems on your system. Removing it now might not be so harmless.

FWIW, my own devel box shows a similar grep hit in /proc/ioports.