From Bugzilla Helper: User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.7.8) Gecko/20050511 Firefox/1.0.4 Description of problem: When booting into the xen0 kernel, the system appears to lose a significant portion of my total RAM. I should see (nearly?) identical results when performing a 'cat /proc/meminfo' regardless of which kernel I am booting into. Version-Release number of selected component (if applicable): xen-2-20050522 How reproducible: Always Steps to Reproduce: 1. Boot into SMP kernel 2. 'cat /proc/meminfo' 3. Reboot into xen0 kernel 3. 'cat /proc/meminfo' Actual Results: Under SMP kernel: MemTotal: 4153996 kB ... Under xen0 kernel: MemTotal: 903168 kB ... Expected Results: Under XMP kernel: MemTotal: 4153996 kB ... Under xen0 kernel: MemTotal: 4153996 kB ... Additional info: Just for reference sake, here are the versions of all xen related RPMs that I am running... [root@localhost ~]# rpm -qa | grep xen kernel-xen0-2.6.11-1.1369_FC4 kernel-xen0-devel-2.6.11-1.1369_FC4 xen-2-20050522 kernel-xenU-2.6.11-1.1369_FC4 kernel-xenU-devel-2.6.11-1.1369_FC4
This is because the xen kernels do not have highmem enabled. Note that the rest of the memory can still be used by the hypervisor, and for guest domains. Try "xm info" and check how much free memory you have. I will enable highmem in future Xen kernels, but mostly to check what problems that will give, since I do not expect it to work flawlessly...
The 2.6.11-1.1369_FC4xenU kernels also appear to be compiled without BIGMEM support, which is kind of a bummer. I allocated 1024M of ram to a domain in it's /etc/xen/domain config file, but when the domain booted, it only reported 903948. This will definitely prevent me from running a serious production-grade system under Xen.
I have the same problem. I have 4 gb of memory on the host. When I try to create a xenU domain xm -c create my_domain the host machine crash!!!
[root@router xen]# xm list Name Id Mem(MB) CPU State Time(s) Console Domain-0 0 891 0 r---- 9.0 [root@router xen]# xm info system : Linux host : router.ispbrasil.com.br release : 2.6.12-1.1398_FC4xen0 version : #1 SMP Fri Jul 15 01:53:34 EDT 2005 machine : i686 cores : 0 hyperthreads_per_core : 2 cpu_mhz : 2992 memory : 3806 free_memory : 2876 [root@router xen]# [root@router ~]# xm list Name Id Mem(MB) CPU State Time(s) Console Domain-0 0 891 0 r---- 9.0 [root@router ~]# xm balloon 0 256 [root@router ~]# xm list Name Id Mem(MB) CPU State Time(s) Console Domain-0 0 256 0 r---- 10.2 [root@router ~]# xm create -c ispbrasil Using config file "/etc/xen/ispbrasil". crashed !!!! this is the /etc/xen/ispbrasil used to start xenU kernel ="/boot/vmlinuz-2.6.12-1.1398_FC4xenU" memory = 128 name = "ispbrasil" nics = 1 disk = ['file:/vps/ispbrasil/root_fs.ext3,sda1,w','file:/vps/ispbrasil/swap.img, sda2,w'] root = "/dev/sda1 ro"
Newer xen kernels have highmem enabled.