mirror/freebsd
1
0
Fork 0
mirror of https://git.FreeBSD.org/src.git synced 2024-12-15 10:17:20 +00:00
Code Issues Releases Activity

Partially revert previous commit. Calling getit() unconditionally fixed

Browse Source 
a problem that could also be fixed differently without reverting previous
attempts to fix DELAY while the debugger is active (rev 1.204). The bug
was that the i8254 implements a countdown timer, while for (k)db_active
a countup timer was implemented. This resulted in premature termination
and consequently the breakage of DELAY. The fix (relative to rev 1.211)
is to implement a countdown timer for the kdb_active case. As such the
ability to step clock initialization is preserved and DELAY does what is
expected of it.

Blushed: bde :-)
Submitted by: bde
This commit is contained in:
Marcel Moolenaar 2004-07-11 17:50:59 +00:00
parent 70c3c978b9
commit 45cfc0a914
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=131991
2 changed files with 44 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
sys/i386/isa/clock.c
View File

@ -401,10 +401,7 @@ getit(void)
{
int high, low;
#ifdef KDB
if (!kdb_active)
#endif
mtx_lock_spin(&clock_lock);
mtx_lock_spin(&clock_lock);
/* Select timer0 and latch counter value. */
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
@ -412,11 +409,7 @@ getit(void)
low = inb(TIMER_CNTR0);
high = inb(TIMER_CNTR0);
#ifdef KDB
if (!kdb_active)
#endif
mtx_unlock_spin(&clock_lock);
mtx_unlock_spin(&clock_lock);
return ((high << 8) | low);
}
@ -457,8 +450,18 @@ DELAY(int n)
* takes about 1.5 usec for each of the i/o's in getit(). The loop
* takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
* multiplications and divisions to scale the count take a while).
*
* However, if ddb is active then use a fake counter since reading
* the i8254 counter involves acquiring a lock. ddb must not do
* locking for many reasons, but it calls here for at least atkbd
* input.
*/
prev_tick = getit();
#ifdef KDB
if (kdb_active)
prev_tick = 1;
else
#endif
prev_tick = getit();
n -= 0; /* XXX actually guess no initial overhead */
/*
* Calculate (n * (timer_freq / 1e6)) without using floating point
@ -485,7 +488,15 @@ DELAY(int n)
/ 1000000;
while (ticks_left > 0) {
tick = getit();
#ifdef KDB
if (kdb_active) {
inb(0x84);
tick = prev_tick - 1;
if (tick <= 0)
tick = timer0_max_count;
} else
#endif
tick = getit();
#ifdef DELAYDEBUG
++getit_calls;
#endif

33
sys/isa/atrtc.c
View File

@ -401,10 +401,7 @@ getit(void)
{
int high, low;
#ifdef KDB
if (!kdb_active)
#endif
mtx_lock_spin(&clock_lock);
mtx_lock_spin(&clock_lock);
/* Select timer0 and latch counter value. */
outb(TIMER_MODE, TIMER_SEL0 | TIMER_LATCH);
@ -412,11 +409,7 @@ getit(void)
low = inb(TIMER_CNTR0);
high = inb(TIMER_CNTR0);
#ifdef KDB
if (!kdb_active)
#endif
mtx_unlock_spin(&clock_lock);
mtx_unlock_spin(&clock_lock);
return ((high << 8) | low);
}
@ -457,8 +450,18 @@ DELAY(int n)
* takes about 1.5 usec for each of the i/o's in getit(). The loop
* takes about 6 usec on a 486/33 and 13 usec on a 386/20. The
* multiplications and divisions to scale the count take a while).
*
* However, if ddb is active then use a fake counter since reading
* the i8254 counter involves acquiring a lock. ddb must not do
* locking for many reasons, but it calls here for at least atkbd
* input.
*/
prev_tick = getit();
#ifdef KDB
if (kdb_active)
prev_tick = 1;
else
#endif
prev_tick = getit();
n -= 0; /* XXX actually guess no initial overhead */
/*
* Calculate (n * (timer_freq / 1e6)) without using floating point
@ -485,7 +488,15 @@ DELAY(int n)
/ 1000000;
while (ticks_left > 0) {
tick = getit();
#ifdef KDB
if (kdb_active) {
inb(0x84);
tick = prev_tick - 1;
if (tick <= 0)
tick = timer0_max_count;
} else
#endif
tick = getit();
#ifdef DELAYDEBUG
++getit_calls;
#endif