PROBLEM:  (QARS 71519 71520 69899 58458)    (Patch ID: OSF425-684)
********
This patch fixes a problem in which system was consistently crashing by
pressing keys during the transition from firmware callback to OS console
handling.

Stack trace:
   1 panic("kernel memory fault")
   2 trap()
   3 _XentMM()
   4 wsputc()
   5 sccputc()
   6 cnputc()
   7 cons_puts() 
   8 printf() 


PROBLEM:  (HPAQA035X, HPAQC12P0) (PATCH ID: OSF425-900)
********

This patch fixes a "thread_block: interrupt level call"
system panic when logging into the console with real
time preemption mode enabled

An example stack trace is as follows:

   1 panic(s = 0xfffffc000052abb8 = "thread_block: interrupt level call") ["../.
./../../src/kernel/bsd/subr_prf.c":747, 0xfffffc0000293d90]
   2 thread_block() ["../../../../src/kernel/kern/sched_prim.c":2159, 0xfffffc00
002c7eb4]
   3 thread_preempt(thread = 0x26, processor = 0xfffffc00001f2100) ["../../../..
/src/kernel/kern/sched_prim.c":4045, 0xfffffc00002ca8fc]
   4 boot(0x0, 0xfffffc0003e32000, 0x2c0000002c, 0x35, 0x1) ["../../../../src/ke
rnel/arch/alpha/machdep.c":1847, 0xfffffc0000401f80]
   5 panic(s = 0xfffffc000052abb8 = "thread_block: interrupt level call") ["../.
./../../src/kernel/bsd/subr_prf.c":834, 0xfffffc0000293f54]
   6 thread_block() ["../../../../src/kernel/kern/sched_prim.c":2159, 0xfffffc00
002c7eb4]
   7 thread_preempt(thread = 0x35, processor = 0xfffffc00001f2100) ["../../../..
/src/kernel/kern/sched_prim.c":4045, 0xfffffc00002ca8fc]
   8 do_preemption(0xfffffc000059bb60, 0xfffffc0000d149c0,
0xfffffc0000406b9c, 0
x1, 0xfffffc0000000000) ["../../../../src/kernel/kern/parallel.c":659, 0xfffffc0
0002c5220]
   9 swap_ipl_preempt_check(0x7600000000, 0x4b9b5000000000, 0x121fffffc00, 0x140
0000000, 0x205070000000000) ["../../../../src/kernel/arch/alpha/spl.s":455, 0xff