[?BUG?] 2.1.10[12] serial IRQ autoconfig (Ingo, you should read)

Riccardo Facchetti (fizban@tin.it)
Sat, 16 May 1998 15:30:31 +0200 (MET DST)


this one is to report a bug in serial autoconfiguration.
In my rc scripts I used to have the following:

setserial /dev/ttyS0 auto_irq skip_test autoconfig
setserial /dev/ttyS1 auto_irq skip_test autoconfig
setserial /dev/ttyS2 auto_irq skip_test autoconfig
setserial /dev/ttyS3 auto_irq skip_test autoconfig

Yes, I have 4 serial ports, all in use.

With 101 and 102, the irq detection no longer works because the auto_irq
returns an IRQ=0 for all the 4 serial ports.

To regain control of my serial hardware, I have changed the rc.serial
script to do:

setserial /dev/ttyS0 irq 4 spd_vhi
setserial /dev/ttyS1 irq 3 spd_vhi
setserial /dev/ttyS2 irq 5 spd_vhi
setserial /dev/ttyS3 irq 2

Relevant hardware:
Tyan Tomcat III Dual, 2xP200 classic (SMP kernel)
RAM 96 MB, ide0[HD,HD], ide1[HD,CDROM]
ttyS0 and ttyS1 are default Tyan serial ports, ttyS2 is an internal modem
and ttyS3 is a 16450 mounted on an old multi I/O ISA card.

Forcing IRQ number in setserial works well while letting the serial driver
autodetect the irq, don't work at all finding IRQ 0 that seems to me just
a bit bogus :)

Now I am running 102 with the working script and the /proc/interrupts show:

0: 57290 46299 IO-APIC-level timer
1: 3650 2651 IO-APIC-level keyboard
2: 0 0 XT-PIC cascade
4: 1674 995 IO-APIC-level serial
5: 357 148 IO-APIC-level serial
8: 0 0 IO-APIC-level rtc
9: 4533 2849 IO-APIC-level serial
11: 182 18 IO-APIC-level MSS audio codec
13: 1 0 XT-PIC fpu
14: 20344 3744 IO-APIC-level ide0
15: 27130 70503 IO-APIC-level ide1
17: 28 28 IO-APIC-level ncr53c8xx
NMI: 0
IPI: 0

It seems good to me.

After running the broken script with autoconfig, all the serial irqs are
not shown at all.
I don't know if the problem is in APIC/SMP or in serial code or in my
machine. I have seen no reports on linux-kernel about serial autoconf not
working, so I feel the problem may be local to my setup, but ... why is
2.1.96 working well with serial irq autoconf, same setup, and 2.1.10[12]
don't work ?


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