CPU Limitations

Hi,
i have the following problem:
I got a amd opteron server with 32 (4*8) cpus.

Since kvm is only able to created a virtual machine with 16 cpus, i changed KVM_MAX_VCPUS, MAX_VCPUS and MAX_CPUS
as suggested in
http://www.linux-kvm.org/wiki/images/b/be/KvmForum2008$kdf2008_6.pdf

after compiling everything is shows the right number of maximum cpus in the virt-manager,
but it is still not working.

If i start for example my virtual machine with

kvm -m 4000 -smp 30 disk0.img

i get a segmentation fault.
in the logfile it looks like that:

[ 4440.424512] __ratelimit: 18 callbacks suppressed
[ 4440.424523] kvm[7054]: segfault at 1ae5cf6b0 ip 00000000004092ba sp

00007fff3dbb8dc0 error 4 in kvm[400000+1e1000]

Any idee what is missing or what is wrong?

cheers
cornelius

Get a core dump and look at it with gdb, you'll probably see the problem immediately.

Do not meddle in the internals of kernels, for they are subtle and quick to panic.

Hi,
i tried to get some useful informations out of gdb. but it just gives me this:

warning: Can't read pathname for load map: Input/output error. Reading symbols from /lib/libm.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libm.so.6
Reading symbols from /lib/libz.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libz.so.1
Reading symbols from /usr/lib/libasound.so.2...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libasound.so.2
Reading symbols from /usr/lib/libpulse-simple.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpulse-simple.so.0
Reading symbols from /usr/lib/libgnutls.so.26...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgnutls.so.26
Reading symbols from /lib/libpthread.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libpthread.so.0
Reading symbols from /lib/librt.so.1...
(no debugging symbols found)...done.
Loaded symbols for /lib/librt.so.1
Reading symbols from /lib/libutil.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libutil.so.1
Reading symbols from /usr/lib/libX11.so.6...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libX11.so.6
Reading symbols from /usr/lib/libSDL-1.2.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libSDL-1.2.so.0
Reading symbols from /lib/libncurses.so.5...
(no debugging symbols found)...done.
Loaded symbols for /lib/libncurses.so.5
Reading symbols from /lib/libc.so.6...(no debugging symbols found)...done.
Loaded symbols for /lib/libc.so.6
Reading symbols from /usr/lib/libpulse.so.0...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libpulse.so.0
Reading symbols from /lib/libdl.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/libdl.so.2
Reading symbols from /usr/lib/libSM.so.6...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libSM.so.6
Reading symbols from /usr/lib/libICE.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libICE.so.6
Reading symbols from /lib/libcap.so.2...
(no debugging symbols found)...done.
Loaded symbols for /lib/libcap.so.2
Reading symbols from /usr/lib/libgdbm.so.3...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libgdbm.so.3
Reading symbols from /usr/lib/libtasn1.so.3...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libtasn1.so.3
Reading symbols from /lib/libgcrypt.so.11...(no debugging symbols found)...done.
Loaded symbols for /lib/libgcrypt.so.11
Reading symbols from /lib/ld-linux-x86-64.so.2...
(no debugging symbols found)...done.
Loaded symbols for /lib64/ld-linux-x86-64.so.2
Reading symbols from /usr/lib/libxcb.so.1...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libxcb.so.1
Reading symbols from /usr/lib/libdirectfb-1.0.so.0...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdirectfb-1.0.so.0
Reading symbols from /usr/lib/libfusion-1.0.so.0...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libfusion-1.0.so.0
Reading symbols from /usr/lib/libdirect-1.0.so.0...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libdirect-1.0.so.0
Reading symbols from /lib/libuuid.so.1...(no debugging symbols found)...done.
Loaded symbols for /lib/libuuid.so.1
Reading symbols from /lib/libattr.so.1...
(no debugging symbols found)...done.
Loaded symbols for /lib/libattr.so.1
Reading symbols from /lib/libgpg-error.so.0...(no debugging symbols found)...done.
Loaded symbols for /lib/libgpg-error.so.0
Reading symbols from /usr/lib/libXau.so.6...
(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXau.so.6
Reading symbols from /usr/lib/libXdmcp.so.6...(no debugging symbols found)...done.
Loaded symbols for /usr/lib/libXdmcp.so.6
Reading symbols from /lib/libnss_files.so.2...
---Type <return> to continue, or q <return> to quit---
(no debugging symbols found)...done.
Loaded symbols for /lib/libnss_files.so.2
(no debugging symbols found)
Core was generated by `kvm -smp 32 /fs2/xen/disk0'.
Program terminated with signal 11, Segmentation fault.
[New process 4665]
[New process 4666]
[New process 4674]
[New process 4670]
[New process 4676]
[New process 4678]
[New process 4669]
[New process 4667]
[New process 4677]
[New process 4686]
[New process 4675]
[New process 4672]
[New process 4679]
[New process 4682]
[New process 4673]
[New process 4681]
[New process 4671]
[New process 4683]
[New process 4689]
[New process 4685]
[New process 4668]
[New process 4690]
[New process 4684]
[New process 4691]
[New process 4687]
[New process 4692]
[New process 4693]
[New process 4694]
[New process 4695]
[New process 4696]
[New process 4680]
[New process 4688]
[New process 4697]
#0 0x00000000004092ba in ?? ()

Do i maybe need to compile KVM with some special debug flags? Is there no patch that increases the number of CPUS?

Cheers,
Cornelius

Am Dienstag, den 28.04.2009, 11:41 +0300 schrieb Avi Kivity:

Use 'gdb /path/to/qemu core_file'

error compiling committee.c: too many arguments to function