AMD Athlon(tm) II X4 620 Processor
RADEON HD4200 Radeon Driver
KDE 4.10.5
Kernel 3.8.0-34-generic
Gigabyte Technology Co., Ltd. GA-MA785GMT-UD2H/GA-MA785GMT-UD2H, BIOS F3 09/16/2009

Sometimes, especially when warm booting, the kernel only recognises 1 core (CPU 0).
Console messages flash up saying something like "No response from CPU 1" ... "No response from CPU 2"...

Normally 4 cores come up as expected but when it starts sulking like this it can take many reboots to correct.

Any thoughts please?

Did you recompile the kernel yourself? If yes, did you set the compilation session for multiprocessors ?
When was the last time you check the disk health?
Does your system run normaly with live cds ?

More information is necessary to spot the problem, please provide as much as you can.

Regards

The F4 BIOS for this mainboards added Core Control options, so it might help to update your BIOS to the latest non-beta version F9.

Thank you for the suggestions chaps.

ukiuki:
It's a stock kernel with CONFIG_NR_CPUS=256.
Disks were fine yesterday.
Live CDs have been problematic sometimes (if kernel version is < 3.7.0 approx.). Newer ones seem OK. Most problematic ones will work with kernel param nolapic_timer.

TobiSGD:
Aha. Sounds like a good first step. I am just going outside to flash my bios and may be some time.

Regards,
Bob.

1 members found this post helpful.

I flashed the bios to F9 05/25/2010.

I couldn't find any Core Control options [EDIT: Found in MIT settings!] in the BIOS Setup, but:

I've rebooted 4 times.

4 cores recognised every time.

Looking good! Thank you.

Regards,

Bob

Please mark thread as solved so others can benefit from it.

Regards

Alas, I spoke too soon! Today I can't get the thing to boot more than 1 core (5 reboots and counting) so I'm still looking for a solution.

Regards,

Bob

After 6 reboots failed to bring up all cores I added nolapic_timer to kernel params.
This worked immediately.

dmesg now lists various timer problems (eg: Could not switch to high resolution mode on CPU x) but high res. is not important to me.
The main thing is that core detection is instantaneous.

It's not a fix, more a workaround; it's clear there are a lot of issues around lapic timers, and AMD C1E it seems.

I'll mark this thread solved in a day or two after a few more boots.

Regards.

Bob

What system and version are you running there?
And what about compile the kernel yourself to fix those problems,
it is clear so far that the stock kernel isn't handling it well.
And in the worse scenario have you grasp the possibility of a faulty hardware?

Regards

It's Mint 15 KDE (other details as per first post).
I don't want to recompile the kernel at the moment as I have development in progress which depend on this particular kernel. I'll probably move to Mint 16 in a few months anyway.
Yes, faulty hardware is always a possibility; but, whether it boots all cores or not, it is a very stable system so I doubt that's the case here. I have seen references to problems with older kernels setting up AMD Athlon chipsets but nothing recent.

Update:
nolapic_timer was not the answer! So I have now reset the BIOS completely (shorted the reset pins on mobo) and am running with nmi_watchdog=0 as a kernel parameter. 3 boots and no failures so far!

Regards,
Bob

I'm going to mark this thread as solved. After resetting the bios and setting nmi_watchdog=0 there hasn't been a single boot failure - must be about twenty boots by now.

Thanks for your help chaps.

Bob