Date: Wed, 7 Jun 1995 19:10:03 -0700 From: Akira SAWADA <sawada@zoo.ncl.omron.co.jp> To: freebsd-bugs Subject: i386/498: bug in checking RTC status at initialization Message-ID: <199506080210.TAA26819@freefall.cdrom.com> In-Reply-To: Your message of Thu, 08 Jun 1995 11:01:50 %2B0900 <199506080201.LAA28549@azalea.zoo.ncl.omron.co.jp>
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>Number: 498
>Category: i386
>Synopsis: bug in checking RTC status at initialization
>Confidential: no
>Severity: serious
>Priority: medium
>Responsible: freebsd-bugs (FreeBSD bugs mailing list)
>State: open
>Class: sw-bug
>Submitter-Id: current-users
>Arrival-Date: Wed Jun 7 19:10:02 1995
>Originator: Akira SAWADA
>Organization:
OMRON Corporation
>Release: FreeBSD 2.0.950412-SNAP i386
>Environment:
IBM PS/55 note
>Description:
At boot time, kernel always says:
Invalid time in real time clock.
Check and reset the date immediately!
In inittodr() of sys/i386/isa/clock.c:
/* Look if we have a RTC present and the time is valid */
if (rtcin(RTC_STATUSD) != RTCSD_PWR)
goto wrong_time;
This RTC status check is failed,
because rtcin(RTC_STATUSD) returns 0x82.
In sys/i386/isa/rtc.h:
#define RTC_STATUSD 0x0d /* status register D (R) Lost Power */
#define RTCSD_PWR 0x80 /* clock lost power */
To check the RTC status,
we should check only the MSB bit of rtcin(RTC_STATUSD).
According to the system manual of PS/55 note,
the lower 7 bits are system reserved.
>How-To-Repeat:
Always at boot time.
>Fix:
The above line:
if (rtcin(RTC_STATUSD) != RTCSD_PWR)
shuould be
if ((rtcin(RTC_STATUSD) & RTCSD_PWR) != RTCSD_PWR)
or
if (!(rtcin(RTC_STATUSD) & RTCSD_PWR))
The corresponding lines in NetBSD-current are here:
(in rtcget() of sys/arch/i386/isa/clock.c)
if (mc146818_read(NULL, MC_REGD) & MC_REGD_VRT == 0) /* XXX softc */
return (-1);
(in sys/dev/ic/mc146818.h)
#define MC_REGD 0xd /* Control register D */
/* MC_REGD_UNUSED 0x7f UNUSED */
#define MC_REGD_VRT 0x80 /* Valid RAM and Time bit */
Thanks in advance.
>Audit-Trail:
>Unformatted:
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