I'm running gentoo-sources-2.6.17-r7 on a Pentium IV HT. Sometimes (quite often) at bootup, only CPU0 is started. Sometimes rebooting will solve the problem, sometimes not. The problem seems (subjectively) to be worse since installing -r7 than it was with -r4.
Created attachment 96354 [details]
Output of dmesg
Created attachment 96355 [details]
Please post dmesg output from a boot where both CPU's are working
Created attachment 97272 [details]
Dmesg with both procs working
This a full dmesg log during a session with both processors working. I've added radeonfb to my kernel which wasn't in the other dmesg log (but this shouldn't matter). I haven't actually seen the problem again since adding radeonfb, but I've only booted a few times since then. I don't think there have been any other changes.
Has this problem reappeared? You could try upgrading your BIOS to the latest version and booting with acpi=off
Reproducing on the latest development kernel (currently 2.6.19-rc3) would also be wise
I've found a BIOS update. The problem hasn't appeared in a few boots, so it may be fixed now. I'll reopen the bug if it comes back. Thanks for your help and time.