FC6 - XEN on Laptop

[tinti]

As I could read in the release note that PAE support is unavailable on Laptop CPU's, I hope I can find some more answers in this forum.
1. Is there another way of using XEN e.g. recompiling XEN without PAE enabled?
2. Is there a way to tweak the grub configuration so that the xen-kernel means PAE is available?

Thanks for any kind of support.
tinti


Happy FC6 user (with working AIGLX now) ;-)

[fcjunkie]

I've managed to get VMware server compiled and running. Don't ask me how - it took a couple hours and I am not sure exactly what was needed. I installed kernel-headers, kernel source, kernel devel, applied the latest vmware patches, and somehow it worked. I am trying the same thing on another machine and I am getting compile errors with vmware telling me the kernel headers don't match the kernel. Odd, since I am using the original fc6 kernel.

[diegof]

I installed FC6 on a notebook and Xen is gone without problems with the standard distribution. I used a i686 kernel without PAE on a T7600 CPU. I tried only WindowsXP. I configured by hand the configuration file.

Diego

[tinti]

Originally Posted by diegof

I installed FC6 on a notebook and Xen is gone without problems with the standard distribution. I used a i686 kernel without PAE on a T7600 CPU. I tried only WindowsXP. I configured by hand the configuration file.

Diego

Where did you got this kernel? Can you also post the output from command:

cat /proc/cpuinfo

Thanks for help

[diegof]

The kernel package is kernel-xen-2.6.18-1.2798.fc6.i686.rpm (standard)

[diego@timb104034 ~]$ cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz
stepping : 6
cpu MHz : 2333.000
cache size : 4096 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 : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic 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 tm2 cx16 xtpr lahf_lm
bogomips : 4665.26

processor : 1
vendor_id : GenuineIntel
cpu family : 6
model : 15
model name : Intel(R) Core(TM)2 CPU T7600 @ 2.33GHz
stepping : 6
cpu MHz : 2333.000
cache size : 4096 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 : 10
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic 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 tm2 cx16 xtpr lahf_lm
bogomips : 4660.55

The most important flag for virtualization is vmx

Diego

[tinti]

This looks to me that you have a brand new notebook, without a Intel centrino but with the new technologie of dual mobile core. Theese processors are PAE capable.

Thanks for your post.

[nfear24]

How do you disable PAE support from the xen-kernel. I dont want it because it causes a panic, so how do you disable it?

[tinti]

If you get a kernel panic, you don't have a PAE capable processor. I don't know how to disable the kernel PAE support, because I didn't find the SRPM's for the PAE kernel, maybe there is a .spec file file for rebuilding the PAE kernel when you download the default kernel SRPM file?

When your installation only includes the PAE kernel, you should reinstall your FC6 and pay attention during installation that you don't select XEN or any other virtualization. After this installation you will have a normal environment with a normal x86 kernel.

[nfear24]

Yep I know I dont have a PAE processor but you dont need PAE to use the xen kernel. I think its a glitch in fc6 because it should automatically detect if you have one or not. It shouldnt enable it by default. Like they did in fc5.

[engwnbie]

Originally Posted by nfear24

Yep I know I dont have a PAE processor but you dont need PAE to use the xen kernel. I think its a glitch in fc6 because it should automatically detect if you have one or not. It shouldnt enable it by default. Like they did in fc5.

You are wrong you do need it for FC6 as posted here.
http://fedoraproject.org/wiki/FedoraXenQuickstartFC6
Para-virtualized guests
Any x86_64, or ia64 CPU is supported for running para-virtualized guests. To run i386 guests requires a CPU with the PAE extension. Many older laptops (particularly those based on Pentium Mobile / Centrino) do not have PAE support. To determine if a CPU has PAE support, run the following command:

$ grep pae /proc/cpuinfo
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow up ts
The above output shows a CPU that does have PAE support. If the command returns nothing, then the CPU does not have PAE support.

New PAE Requirement for i386 Guests. Previous versions of the Xen kernel did not require PAE support. This change will affect laptop users.

[nfear24]

Originally Posted by engwnbie

You are wrong you do need it for FC6 as posted here.
http://fedoraproject.org/wiki/FedoraXenQuickstartFC6
Para-virtualized guests
Any x86_64, or ia64 CPU is supported for running para-virtualized guests. To run i386 guests requires a CPU with the PAE extension. Many older laptops (particularly those based on Pentium Mobile / Centrino) do not have PAE support. To determine if a CPU has PAE support, run the following command:

$ grep pae /proc/cpuinfo
flags : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow up ts
The above output shows a CPU that does have PAE support. If the command returns nothing, then the CPU does not have PAE support.

New PAE Requirement for i386 Guests. Previous versions of the Xen kernel did not require PAE support. This change will affect laptop users.

I still dont find this to be TRUE. Yes by default you do need PAE in fc6 but its not required to run xen I dont think. People have it running on older centrino's. check out this: http://www.dharwadkar.com/weblog/fc6_kernel

I found one list on XEN which talked about the same issue that I was facing and it noted that a workaround to the problem I was facing was to use

swiotlb=force

as a kernel parameter when booting.

Also: xen works great without a PAE cpu - but you need modified guests (modified fc6 kernels are availiable via yum)
the advantage of a cpu with PAE is that you can run unmodified guests like windows