[laptop-discuss] Re: Re: Re: Cardbus report: PCMCIA CDMA modem

[Vincent R Wang]

Douglas Atique wrote:

>>The first argument of ndi_devi_enter() is a dev_info
>>structure. It has
>>a devi_busy_thread member showing the thread that
>>blocks the caller of
>>ndi_devi_enter(). 
>>    
>>
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>I don't understand. Is this some sort of cooperative synchronization? Do you mean that one thread can "see" another thread that is blocking it? I thought all synchronization was handled in a very low level (even lower than device drivers and I/O) and was thus transparent to any code except the scheduler and maybe a few other very privileged bits...
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This is very low level kernel code, with sufficient privilege. See the 
source code of ndi_devi_enter() in usr/src/uts/common/os/devcfg.c. 
You'll immediately understand what's going on.

>>mt_config_thread() and config_grand_children() are
>>deadlocking each other.
>>    
>>
>
>I am not familiar with the code, so forgive me for this stupid question: If this deadlock is being caused by power management code, can we simply disable power management (I mean by commenting out the power management driver entry points) for the cardbus-related drivers? Could that provide a temporary workaround?
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Disabling power management does appear to workaround the deadlock. I've 
just tried it. It worked for me:
In usr/src/uts/common/pcmcia/nexus/pcmcia.c
@@ -403,12 +403,6 @@
         * implement it.
         */

-       if (pm_create_components(dip, 1) != DDI_SUCCESS) {
-               cmn_err(CE_WARN, "%s: not power managed\n",
-                       ddi_get_name_addr(dip));
-       } else {
-               pm_set_normal_power(dip, 0, 1);
-       }

        /*
         * setup the info necessary for Card Services/SocketServices
Need to recompile pcmcia from usr/src/uts/intel/pcmcia/Makefile.

DISCLAIMER: This is _not_ an official patch from Sun. Use at your own risk.

I'll investigate further to see if there's a better solution.

>By the way, I just downloaded and installed SXCR b51 and it deadlocks right on the first reboot after installation (while doing the "Configuring devices"). I also found out that my Toshiba BIOS has a PC Card configuration setting that can be set to "Automatic", "PCIC compatible" or "Cardbus/16-bit". On automatic, the b51 hangs on boot. On "Cardbus/16-bit" it panics on some dev configuration routine. I haven't tested "PCIC compatible" because I think it is not what we want.
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Please use Cardbus/16-bit.

Toshiba laptops usually have a serial port. You may connect the RS232 
port to another PC to diagnose the problems during boot.
    - If it panicks, check the stack trace.
    - If it hangs, press F1-a to drop into kmdb and use $<threadlist to 
show all the threads. Need to edit the grub menu(press 'e' )  and use 
the following boot options:
    grub edit> kernel /platform/i86pc/multiboot -B console=ttya -k

Vincent.


>I wish I could understand what is going on and investigate the code myself.
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