Only one CPU core recognized in Gutsy after updates

Thank you for taking the time to report this bug and helping to make Ubuntu better. Could you please add the full output of 'dmesg' after booting up as an attachment to your bug report? Additionally the specific version of the kernel that you are running would be quite helpful, you can find that out with 'uname -a'. Thanks in advance.

$ uname -a
Linux Possulap 2.6.22-11-generic #1 SMP Mon Sep 17 03:18:44 GMT 2007 x86_64 GNU/Linux

Here's the lspci -vvnn

Here is another dmesg, after a reboot with the irqpoll option removed.
But it breaks my wireless connection etc. to do that.
And the laptop won't boot at all (crashes/freezes) if the acpi=off option is removed, so no output is in logs.

Jukka

Gusty is not recognizing my dual core as well. Here is some info:

alan@desktop:~$ uname -a
Linux desktop 2.6.22-11-generic #1 SMP Mon Sep 17 03:45:58 GMT 2007 i686 GNU/Linux

alan@desktop:~$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 107
model name : AMD Athlon(tm) 64 X2 Dual Core Processor 4800+
stepping : 1
cpu MHz : 1000.000
cache size : 512 KB
physical id : 0
siblings : 1
core id : 0
cpu cores : 1
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8legacy 3dnowprefetch ts fid vid ttp tm stc 100mhzsteps
bogomips : 2011.01
clflush size : 64

Attached is my full dmesg after a fresh boot.

Attached is my lspci -vvnn as well.

For me, adding "acpi=off" as a kernel boot option to menu.lst made my second core work. I can't adjust their speeds, but at least both are working.

OK, that's good. Mine crashes/freezes without the acpi=off option at boot.
Now we know that it is a different problem with Intel and AMD CPU's, perhaps.

Same with me, experimented a bit with kernel-paramenters. acpi=ht will work but breaks gdm. Have to startx manually. However only one cpu is detected.

same problem here (intel core 2 duo) - full dmesg output attached, interestingly including:

[ 0.000000] Processor #1 6:15 APIC version 20
[ 0.000000] WARNING: NR_CPUS limit of 1 reached. Processor ignored.

uname -sar
Linux my-laptop 2.6.22-11-386 #1 Mon Sep 17 03:17:38 GMT 2007 i686 GNU/Linux

hmm... i was using linux-image-i386, works fine with linux-image generic here.

davie: do you also have the acpi=off option enabled?
And do you have the freeze problem at startup without acpi=off as e.g. in http://ubuntuforums.org/showthread.php?t=553309 or in
bug 140635 ?

Gutsy works for me:

$ uname -a
Linux 4lom 2.6.22-11-generic #1 SMP Mon Sep 17 03:45:58 GMT 2007 i686 GNU/Linux
$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 6
model name : Intel(R) Pentium(R) D CPU 3.00GHz
stepping : 4
cpu MHz : 2992.886
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 6
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl vmx est cid cx16 xtpr lahf_lm
bogomips : 5990.48
clflush size : 64

processor : 1
vendor_id : GenuineIntel
cpu family : 15
model : 6
model name : Intel(R) Pentium(R) D CPU 3.00GHz
stepping : 4
cpu MHz : 2992.886
cache size : 2048 KB
physical id : 0
siblings : 2
core id : 1
cpu cores : 2
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 6
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe nx lm constant_tsc pni monitor ds_cpl vmx est cid cx16 xtpr lahf_lm
bogomips : 5985.29
clflush size : 64

Modern hardware provides no way of enumerating CPUs without using ACPI, so it's normal for you to only see one if you disable ACPI. There's no way to avoid that, so please open another bug about the ACPI issue and we'll see if we can fix that.

The problem is that we cannot see the other cpu UNLESS we have acpi disabled.

The problem is that the computer does not boot with ACPI enabled, and does not see the second processor if it is disabled. So why an earth would you not fix it?!?!?!?!?!?!?!?!?!?

Alan: No, you seem to have a different bug. Please file that one separately
Juksu: Your computer simply provides no way for us to tell it has more than one processor unless ACPI is enabled, so the only way we can fix this is to fix your problem with ACPI. Please open a separate bug for that.

Oops, sorry. Made assumptions. IN MY CASE, I cannot utilize the second core UNLESS acpi IS disabled.

I DID FILE A BUG REPORT DAYS AGO ABOUT THE ACPI ISSUE BUT IT WAS STAMPED DUPLICATE BY SOMEONE
https://bugs.launchpad.net/ubuntu/+source/linux-source-2.6.22/+bug/140651

The other thread is not named ACPI and is not deemed to be of high importance, which is not correct considering the show-stopper nature of this bug.

Works now, good work, thanks.

Per a decision made by the Ubuntu Kernel Team, bugs will longer be assigned to the ubuntu-kernel-team in Launchpad as part of the bug triage process. The ubuntu-kernel-team is being unassigned from this bug report. Refer to https://wiki.ubuntu.com/KernelTeamBugPolicies for more information. Thanks.