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Old 08-19-05, 08:15 AM   #13
JaXXoN
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Join Date: Jul 2005
Location: Munich
Posts: 910
Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Quote:
Originally Posted by jbaietto
I'm a little scared about updating the video bios
In theory, a wrong BIOS could demage a card, i.e. when GPU voltage
is set to a much higher value then the card can bear and/or fans
are not operating. Pratically, the card simple won't start working
at all if something doesn't fit and you can savely restore the original
BIOS using the second video card (don't flash both at the same time,
otherwise you may need a third card to fix it).

Quote:
Originally Posted by jbaietto
as the cards are not cheap.
I know, i also have two of them :-)

Quote:
Originally Posted by jbaietto
I plan to use the system for some real-time applications.
Just out of curiousity, which real-time variant do you intend to use?
RTAI, RTLinux, real-time preemption ... ?

Please note that when starting a 3D application, the nvidia kernel
driver module invokes a "wbinv" instruction that can cause
a latency up to 130 microseconds (measured with an 4200Ti on
an Asus A7N8X) - i didn't yet made extensive latency tests on
A8N-SLI/4400+ with 7800GTX. I considers this "wbinv" instruction
in the driver to be a bug :-)

Quote:
Originally Posted by jbaietto
According to /proc/iomem the kernel is in fairly low physical memory:

00100000-7ffcffff : System RAM
00100000-0035e7ed : Kernel code
0035e7ee-004a0ea7 : Kernel data
That's the same as for i386 on my machine. in fact, my second
7800GTX is also mapped at 0xc0000000:

cat /proc/iomem
[...]
c0000000-cfffffff : PCI Bus #02
c0000000-cfffffff : 0000:02:00.0

cat /proc/pci
[...]
Bus 2, device 0, function 0:
Class 0300: PCI device 10de:0091 (rev 161).
IRQ 19.
Non-prefetchable 32 bit memory at 0xd0000000 [0xd0ffffff].
Prefetchable 64 bit memory at 0xc0000000 [0xcfffffff].
Non-prefetchable 64 bit memory at 0xd1000000 [0xd1ffffff].
I/O at 0x9000 [0x907f].

So i don't think that's an issue.

BTW.: i can remember that i also had that error messages on some
embedded PowerPC board, but the PCI device in question worked
flawlessly. Did you actually tried to start an X-Server on the
second card? I added 'BusID "2:0:0"' in the device section of
/etc/X11/xorg.conf for testing. In your case it's probably "129:0:0" or "81:0:0",
depending on if Xorg uses decimal or hexadecimal notation for BusID
(I think it's decimal, but i could be wrong).

regards

Bernhard
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Old 08-19-05, 08:34 AM   #14
JaXXoN
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Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Some more hints:

According to the dmesg in your nvidia-bug-report, device 10de:0059
(probably the on-board sound) on 0:4:0 has also resource problems:

PCI: Cannot allocate resource region 0 of device 0000:00:04.0

Maybe you should disable any on-board hardware in the BIOS menu
that you don't need for minimal testing (Firewire, Sound, Ethernet,
IDE/SATA controller, using USB v1.1 (OHCI) instead of v2.0 (EHCI).
Maybe you can eliminate the conflict that way. If true, then you
can re-enable one device after the other until you find out the
guilty one.

Second, you may try "pci=noacpi" as kernel boot option.

Third, what does "lspci -vvv" say (invoked as root)?

regards

Bernhard
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Old 08-19-05, 08:52 AM   #15
jbaietto
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Location: Fort Lauderdale, Florida
Posts: 12
Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Quote:
Just out of curiousity, which real-time variant do you intend to use?
RTAI, RTLinux, real-time preemption ... ?
I run Concurrent's RedHawk Linux. Here's a link if you're curious:

http://www.ccur.com/isd_solutions_redhawklinux.asp?o9=1

Quote:
Please note that when starting a 3D application, the nvidia kernel
driver module invokes a "wbinv" instruction that can cause
a latency up to 130 microseconds
Interesting. Concurrent modifies the open-source portion of the nvidia driver to take advantage of pre-allocated grapics buffers in order to eliminate memory allocation related non-determinism in the driver. They'll be releasing an updated kernel with 7676 support shortly so I'll make sure to bring the wbinv issue to their attention.

If you're curious about their modifications to the driver, check out "Cross Processor Interrupts on Shielded CPUs" (Appendix G) in their User's Guide:

http://www.ccur.com/isdmanuals/2RedH...sers_Guide.pdf

Quote:
Did you actually tried to start an X-Server on the second card?
Yes, many times, but I got tired of seeing the failures so I took it out of xorg.conf. The BusID is in decimal. It tries to initialize the card but gets confused quickly and aborts.

Take care,
Jason
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Old 08-19-05, 10:00 AM   #16
JaXXoN
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Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Quote:
Originally Posted by jbaietto
They'll be releasing an updated kernel with 7676 support shortly so I'll make sure to bring the wbinv issue to their attention.
I guess the 3D application is running on the (non-shielded) application
processor rather than the (shielded) real time processor? In this case,
the wbinv shouldn't harm any real time application running on the
shielded CPU. Anyway, what are your latency requirements?
AFAIK, the shielded CPU real time variant doesn't yet use Ingo
Molnars real time preemption patch, so i.e. worst case interrupt
latencies are about 500 microseconds. Those are caused by the
nvidia driver - under heavy hard disk and ethernet load, interrupt
latencies are typically below 100 microseconds. For 3D visualization,
i would say even 10 milliseconds should be good enough in most
cases, but YMMV.

regards

Bernhard
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Old 08-19-05, 03:03 PM   #17
jbaietto
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Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Quote:
I guess the 3D application is running on the (non-shielded) application
processor rather than the (shielded) real time processor?
Yes, that's the current plan.

Quote:
AFAIK, the shielded CPU real time variant doesn't yet use Ingo
Molnars real time preemption patch
The RedHawk kernel has included a real-time patch for a couple of years now that is conceptually very similar to Ingo's latest patches.

Take care,
Jason
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Old 08-20-05, 02:21 PM   #18
jbaietto
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Posts: 12
Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

Just a quick follow up. None of the kernel boot-option changes appeared to help.

Messing with acpi settings caused lots of breakage: ATA fatal errors, no USB devices found and then init hung.

Turning off smp resulted in a kernel panic shortly after boot. I then booted the non-SMP kernel (still 64-bit) but it had the original problem.

I'll try a 32-bit Linux next, but it may take me a while to get around to it.

Take care,
Jason
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Old 08-21-05, 05:45 PM   #19
JaXXoN
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Default Re: Two video cards, one AWOL (v7676 + 7800GTXs)

BTW.: your mainboard has two x8 slots and there are no (or no high) electronic
parts mounted behind those slots. If you are very courageously, then you could
remove the ends of those slots so that the x16 cards can fit in (i did that for
the x4 slot on a Asus A8N-SLI Premium, so that i can operate an ARC-1210
raid controller in parallel to my two 7800GTX cards - works without any
problems). However, before doing so, i strongly recommend to practice
with an old/broken PCI board: don't just try to cut out the plastic with a knive - this
will for sure heavily demage the slot. Since i was limited in hardware tools, I used
a soldering iron in the way like you would use a knive to pull off butter.

Anyway, i certainly don't provide any warranties :-)

regards

Bernhard
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