aic7x^3: locks up (2.4.19 up to .21-pre7)

From: Christian Vogel (chris@obelix.hedonism.cx)
Date: Fri Apr 18 2003 - 09:16:25 EST


Hi,

short version: I have two aic7xxx SCSI-controllers in my machine and I
can reproduce hard lockups when accessing both simultaneously.
This phenomenon was not present on 2.4.18 vanilla and appears
since 2.4.19 up to (last one tested 2.4.21-pre7). 2.4.20-ac2 also
is affected.

I have two aic7xxx controllers (one 2940U, one UW) on a VIA KT266-based
motherboard with the following SCSI devices connected to them.

 2940UW ----(internal 68pin)---- IBM DNES-318350W (Disk) on ID 0
                              |
                              +- (active terminator)

 2940U ----(internal 50pin)---- PLEXTOR PX-20TS (CD) on ID 5
    | |
    +--- YAMAHA CRW4416S +- ARCHIVE Python 27871-XXX (Streamer)
  (ext) (CD-Writer) |
                              +- (passive terminator)

This setup seemed to be stable for a long time.
Now I discovered (and verified) that I have problems
with concurrent access between the 2940UW and the 2940U.

A test looks like this:

1.) boot acpi=off aic7xxx=verbose console=ttyS1 init=/bin/sh
2.) init-2.05a# /sbin/devfsd /dev
3.) init-2.05a# cat /dev/scsi/host1/bus0/target6/lun0/cd >/dev/null &
4.) init-2.05a# ls /bin
  (hearing harddisk clicking a little...)
 ---> tadaa: instant hang. No response whatsoever, cursor of the
        matrox framebuffer stops blinking

It's also possible to try burning a CD, this also locks the machine
(and that's how I discovered it, who needs CDs anyway these days :-) ).

Permutations I have tested:
  - acpi=off/on
  - internal/external cable of the 2940U connected/disconnected
  - reading Plextor/Yamaha

Affected kernels:
  - kernel 2.4.18 works without any problems
  - kernel 2.4.19, 20, 21-pre7, 20-ac2 hangs

I don't think that cabling of the SCSI-bus is an issue, because
the problem appears on both the internal and the external bus
independently and it always appears as soon as I access the *other*
SCSI adapter.... And using 2.4.18 I burned many CDs flawlessly...

/proc/interrupts:
  0: 6647 XT-PIC timer
  1: 135 XT-PIC keyboard
  2: 0 XT-PIC cascade
  4: 1 XT-PIC serial
  8: 1 XT-PIC rtc
 11: 3311 XT-PIC aic7xxx, VIA8233
 12: 1084 XT-PIC PS/2 Mouse
 14: 17 XT-PIC ide0
 15: 1114 XT-PIC aic7xxx, eth0, Ensoniq AudioPCI, usb-uhci
NMI: 0
LOC: 6613
ERR: 10
MIS: 0

Attachments (too long to have inline conveniently):

 - 2.4.21-p7-no_acpi.txt -> sample boot. 2.4.21-p7 with acpi
                        patch but acpi disabled

 - lspci -> output of lspci -v -v -v

 - config-2.4.21... -> .config from 2.4.21-p7 kernel used

If I can help with providing some more datapoints, feel free
to email me.

        Chris

-- 
Gates' Law: Every 18 months, the speed of software halfes.




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