cvs commit: src/sys/i386/i386 trap.c src/sys/amd64/amd64 trap.c

Bruce Evans bde at
Sun Jun 26 19:44:55 GMT 2005

On Sat, 25 Jun 2005, Marcel Moolenaar wrote:

> On Jun 25, 2005, at 3:14 PM, Stephan Uphoff wrote:
>> ups         2005-06-25 22:14:42 UTC
>>   FreeBSD src repository
>>   Modified files:
>>     sys/i386/i386        trap.c
>>     sys/amd64/amd64      trap.c
>>   Log:
>>   Disable the interrupts in trap_fatal before calling kdb_trap.
>>   (required now that critical sections no longer block interrupts)
> Why does this only apply to i386 and amd64?

Because it is a wrong fix.  Many arches used to hard-disable interrupts
in their MD kdb_trap(), but this rotted to critical_enter() in rev.1.1
of subr_kdb.c.  "Many arches":

alpha: used intr_disable(), but misplaced it so that it didn't protect
        the state global
amd64: used disable_intr() correctly
arm: used only splhigh()
i386: used disable_intr() correctly
ia64: used intr_disable() correctly
sparc64: no locking except that given by cndbctl()

Loss of cndbctl() for all arches in rev.1.1 of subr_kdb.c is more
serious.  critical_enter() blocks most things, but calling cndbctl()
is critical for the console drivers that depend on it to keep track
of when console i/o is done from within ddb.  Mainly syscons depends
on it.  Calls to cndbctl() used to only be missing for arm.


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