Description of problem: Dell PowerEdge 1950 fully RHN patched (firmware + software) fails to recognize the full amount of installed RAM when booted with the latest xen-kernel. The problem does not occur with non xen kernels, where the full amount of RAM memory is detected properly. Version-Release number of selected component (if applicable): Red Hat Enterprise Linux Server release 5.3 (Tikanga) kernel-xen.x86_64 2.6.18-128.1.10.el5 grub.x86_64 0.97-13.2 (in case grub is to blame) How reproducible: Highly reproducible on all Dell PowerEdge 1950 (E5420) boxes Steps to Reproduce: 1. Hardware test and fully RHN update a Dell PE1950 (E5420) system which includes virtualization entitlement 2. Boot the system into the non-xen enabled kernel. Observe the output of 'free'. 3. Boot the system into the xen-kernel. Observe the output of free. 4. Repeats steps 2-3 at least twice to make sure the failure is consistent. Actual results: [root@cnkeeper ~]# free total used free shared buffers cached Mem: 33554432 1068904 32485528 0 18264 164664 -/+ buffers/cache: 885976 32668456 Swap: 32767992 0 32767992 Expected results: [root@cnkeeper ~]# free total used free shared buffers cached Mem: 64971128 432788 64538340 0 27500 289052 -/+ buffers/cache: 116236 64854892 Swap: 32767992 0 32767992 (as reported by the non-xen kernel Additional info: i)A similar incident report on FC9 can be found on id 250299 ii)Snapshot of dmidecode of the PE 1950 (E5420) system: BIOS Information Vendor: Dell Inc. Version: 2.5.0 Release Date: 09/12/2008 Address: 0xF0000 Runtime Size: 64 kB ROM Size: 1024 kB Characteristics: ISA is supported PCI is supported PNP is supported BIOS is upgradeable BIOS shadowing is allowed ESCD support is available Boot from CD is supported Selectable boot is supported EDD is supported Japanese floppy for Toshiba 1.2 MB is supported (int 13h) 5.25"/360 KB floppy services are supported (int 13h) 5.25"/1.2 MB floppy services are supported (int 13h) 3.5"/720 KB floppy services are supported (int 13h) Print screen service is supported (int 5h) 8042 keyboard services are supported (int 9h) Serial services are supported (int 14h) Printer services are supported (int 17h) CGA/mono video services are supported (int 10h) ACPI is supported USB legacy is supported BIOS boot specification is supported Function key-initiated network boot is supported Targeted content distribution is supported BIOS Revision: 2.5
The dom0 kernel is limited to 32GB by default, but the full amount of memory is still available for guests. This is done to limit the overhead of managing that much memory in dom0 - after all, if people install kernel-xen, they will do so in order to run guests. Type 'xm info' or look at the virt-manager graphical interface to see all of system memory.