acpi breaks async interface

[Juraj Bednar]

Hello,

 I just found a strange thing in 2.4.1 (don't know, if the same
occured in 2.4.0) and 2.4.1-ac3. When I enable ACPI, my serial
port starts to drop some characters. When making ppp over this
and doing ping, it causes great packet losts. If I turn ACPI in
this configuration off, it works with no problems. I tried to
switch serial port IRQ to other one (was 4, switched to 3 and
tested) and it didn't help. Maybe something's broken.

 ACPI related boot messages:

Feb  4 23:21:58 idoru kernel: ACPI: Core Subsystem version [20010125]
Feb  4 23:21:58 idoru kernel: ACPI: Subsystem enabled
Feb  4 23:21:58 idoru kernel: ACPI: System firmware supports: C2 C3
Feb  4 23:21:58 idoru kernel: ACPI: System firmware supports: S0 S1 S4 S5

[root@idoru log]# cat /proc/interrupts 
           CPU0       
  0:      57278          XT-PIC  timer
  1:       2658          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  4:      49530          XT-PIC  serial
  5:          1          XT-PIC  soundblaster
 10:         15          XT-PIC  aha152x
 11:         60          XT-PIC  eth0
 12:      27772          XT-PIC  PS/2 Mouse
 14:     213118          XT-PIC  ide0
 15:       3298          XT-PIC  ide1
NMI:          0 
LOC:          0 
ERR:          0

           Have a nice day,
                  Juraj.