Xen Grub configuration

Felipe Alfaro Solana felipe_alfaro at linuxmail.org
Sat Jan 8 18:02:03 UTC 2005


Hi!

After installing kernel-xen0 from RawHide, the following lines were 
added to my /boot/grub/menu.lst:

title Fedora Core (2.6.10-1.1074_FC4xen0)
	root (hdX,X)
	kernel /vmlinuz-2.6.10-1.1074_FC4xen0 ro root=/dev/XXX
	initrd /initrd-2.6.10-1.1074_FC4xen0.img

However, this is incorrect, as vmlinuz-2.6.10-1.1074-FC4xen0 cannot be 
booted by GRUB directly (must be ran under the control of the XEN 
hypervisor). Instead, GRUB *must* boot /boot/xen.gz which is the XEN 
hypervisor kernel. Thus, /boot/grub/menu.lst should look like this:

title Fedora Core (2.6.10-1.1074_FC4xen0)
	root (hdX,X)
	kernel /xen.gz dom0_mem=400000 noreboot
	module /vmlinuz-2.6.10-1.1074_FC4xen0 ro root=/dev/XXX
	module /initrd-2.6.10-1.1074_FC4xen0.img

Note how now xen.gz is the kernel, and take note of the "dom0_mem" 
kernel parameter which is needed for XEN to allocate physical memory 
for XEN's domain 0, Omitting the "dom0_mem" parameter makes XEN 
allocate too little memory for the domain 0 kernel which, as result, 
will crash with an Out of Memory error.

"dom0_mem=400000" could default to "dom0_mem=130000" instead. This 
shouldn't be much of a problem since if we try to allocate more memory 
than the maximum available RAM, XEN hypervisor will complain. However, 
omitting "dom0_mem" will make the Linux kernel crash and reboot, which 
is much worse.

Should I fill in a bug report for this?
Thanks.




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