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Aurora
l33t
Joined: 26 Sep 2003
Posts: 658
Location: Classified
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 Posted: Fri Sep 07, 2007 1:40 am Post subject: xen + gentoo in domU |
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I know someone who is trying to run a Gentoo domU image (the one found on jailtime) on his server. I'm relatively certain that the user is not running Gentoo as the dom0.
I'm still slightly unsure about the whole xen domU + dom0 kernel process. Here's a brief rundown of how the jailtime Gentoo domU image works (to the best of my knowledge):
- The entire OS is contained in one large .img file
- The .img file has a /boot directory in it, but the /boot directory has nothing inside (I imagine this is normal
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- The fstab inside the jailtime image has sda1 mounted as root (seems to work fine )
So here's where I'm confused. From what I understand, the kernel for the domU is stored in the dom0's file system. It seems the xen .cfg file tells the xen virtual machine what kernel to boot up (and the kernel is located in the dom0's /boot, or some other directory in the dom0's file system) when the VM starts up. Correct?
This is the big question: can the person run a Gentoo domU without running a Gentoo dom0? If so, how? How can someone running, for example, Fedora 7 run Gentoo in a domU if the xen domU kernel is a Fedora xen kernel?
I hope my question made sense.
Thanks!
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Aurora
l33t
Joined: 26 Sep 2003
Posts: 658
Location: Classified
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| Posted: Fri Sep 07, 2007 5:27 pm Post subject: |
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Small bump... I'm still tinkering with this problem and am still clueless after having scoured the net. 
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Sven Vermeulen
Retired Dev
Joined: 29 Aug 2002
Posts: 1345
Location: Mechelen, Belgium
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| Posted: Thu Sep 13, 2007 4:58 pm Post subject: Re: xen + gentoo in domU |
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| Aurora wrote: |
So here's where I'm confused. From what I understand, the kernel for the domU is stored in the dom0's file system. It seems the xen .cfg file tells the xen virtual machine what kernel to boot up (and the kernel is located in the dom0's /boot, or some other directory in the dom0's file system) when the VM starts up. Correct?
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Correct.
| Aurora wrote: |
This is the big question: can the person run a Gentoo domU without running a Gentoo dom0? If so, how? How can someone running, for example, Fedora 7 run Gentoo in a domU if the xen domU kernel is a Fedora xen kernel?
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Yes. It doesn't matter what distribution dom0 and domU's are running. After all, dom0 just needs its Xen-enabled kernel with back-end drivers while the dumU's need a Xen-enabled kernel with front-end drivers.
So you can perfectly run Gentoo in a domU if the xen dumU kernel is a Fedora xen kernel, as long as it is correctly configured.
See also Gentoo in Xen Guide.
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Aurora
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Joined: 26 Sep 2003
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| Posted: Sat Sep 15, 2007 3:43 pm Post subject: |
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Thanks for the reply, Sven.
I created a xen machine using the dd method described in the wiki. I then got a copy of the domU kernel that the person is trying to use with the Gentoo domU.
Based on the kernel bootup messages, this is not a Gentoo xen-sources kernel.
When the person tries to boot up, here's what is seen in the xen console:
| Code: | [root@localhost ~]# xm create gentoo && xm console gentoo
Using config file "/etc/xen/gentoo".
Started domain gentoo
Linux version 2.6.18-4-xen-686 (Debian 2.6.18.dfsg.1-12etch2) (dannf@debian.org) (gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)) #1 SMP Thu May 10 03:24:35 UTC 2007
BIOS-provided physical RAM map:
Xen: 0000000000000000 - 0000000008800000 (usable)
0MB HIGHMEM available.
136MB LOWMEM available.
ACPI in unprivileged domain disabled
Built 1 zonelists. Total pages: 34816
Kernel command line: root=/dev/sda1 ro 4
Enabling fast FPU save and restore... done.
Enabling unmasked SIMD FPU exception support... done.
Initializing CPU#0
PID hash table entries: 1024 (order: 10, 4096 bytes)
Xen reported: 2533.244 MHz processor.
Dentry cache hash table entries: 32768 (order: 5, 131072 bytes)
Inode-cache hash table entries: 16384 (order: 4, 65536 bytes)
Software IO TLB disabled
vmalloc area: c9000000-f51fe000, maxmem 2d7fe000
Memory: 115824k/139264k available (1582k kernel code, 15100k reserved, 585k data, 148k init, 0k highmem)
Checking if this processor honours the WP bit even in supervisor mode... Ok.
Calibrating delay using timer specific routine.. 6338.45 BogoMIPS (lpj=12676917)
Security Framework v1.0.0 initialized
SELinux: Disabled at boot.
Capability LSM initialized
Mount-cache hash table entries: 512
CPU: Trace cache: 12K uops, L1 D cache: 8K
CPU: L2 cache: 512K
Checking 'hlt' instruction... OK.
SMP alternatives: switching to UP code
Freeing SMP alternatives: 12k freed
Brought up 1 CPUs
migration_cost=0
checking if image is initramfs... it is
Freeing initrd memory: 10658k freed
Grant table initialized
NET: Registered protocol family 16
Brought up 1 CPUs
PCI: setting up Xen PCI frontend stub
ACPI: Interpreter disabled.
Linux Plug and Play Support v0.97 (c) Adam Belay
pnp: PnP ACPI: disabled
xen_mem: Initialising balloon driver.
PCI: System does not support PCI
PCI: System does not support PCI
NET: Registered protocol family 2
IP route cache hash table entries: 2048 (order: 1, 8192 bytes)
TCP established hash table entries: 8192 (order: 4, 65536 bytes)
TCP bind hash table entries: 4096 (order: 3, 32768 bytes)
TCP: Hash tables configured (established 8192 bind 4096)
TCP reno registered
audit: initializing netlink socket (disabled)
audit(1189855363.686:1): initialized
VFS: Disk quotas dquot_6.5.1
Dquot-cache hash table entries: 1024 (order 0, 4096 bytes)
Initializing Cryptographic API
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered (default)
RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize
Xen virtual console successfully installed as tty1
Event-channel device installed.
netfront: Initialising virtual ethernet driver.
PNP: No PS/2 controller found. Probing ports directly.
i8042.c: No controller found.
mice: PS/2 mouse device common for all mice
TCP bic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
NET: Registered protocol family 8
NET: Registered protocol family 20
Using IPI No-Shortcut mode
Registering block device major 8
Freeing unused kernel memory: 148k freed
Loading, please wait...
Begin: Loading essential drivers... ...
Done.
Begin: Running /scripts/init-premount ...
FATAL: Error inserting fan (/lib/modules/2.6.18-4-xen-686/kernel/drivers/acpi/fan.ko): No such device
FATAL: Error inserting thermal (/lib/modules/2.6.18-4-xen-686/kernel/drivers/acpi/thermal.ko): No such device
Done.
Begin: Mounting root file system... ...
Begin: Running /scripts/local-top ...
Done.
Begin: Running /scripts/local-premount ...
Done.
ReiserFS: sda1: found reiserfs format "3.6" with standard journal
ReiserFS: sda1: using ordered data mode
ReiserFS: sda1: journal params: device sda1, size 8192, journal first block 18, max trans len 1024, max batch 900, max commit age 30, max trans age 30
ReiserFS: sda1: checking transaction log (sda1)
ReiserFS: sda1: Using r5 hash to sort names
Begin: Running /scripts/local-bottom ...
Done.
Done.
Begin: Running /scripts/init-bottom ...
Done.
4gb seg fixup, process init (pid 1), cs:ip 73:b7e7710a
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7f0ec97
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7edb9cb
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb4dde
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7f1a399
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb826c
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb827a
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb826c
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb827a
4gb seg fixup, process modprobe (pid 707), cs:ip 73:b7eb826c
modprobe: FATAL: Could not load /lib/modules/2.6.18-4-xen-686/modules.dep: No such file or directory
modprobe: FATAL: Could not load /lib/modules/2.6.18-4-xen-686/modules.dep: No such file or directory
INIT: version 2.86 booting
Gentoo Linux; http://www.gentoo.org/
Copyright 1999-2007 Gentoo Foundation; Distributed under the GPLv2
Press I to enter interactive boot mode
* Mounting proc at /proc ...[ oops ]
* The "mount" command failed with error:
proc already mounted
* Since this is a critical task, startup cannot continue.
Give root password for maintenance
(or type Control-D to continue): |
Any ideas on what's going on here? I've tried commenting out the /proc statement in fstab, but the proc fatal error was still there.
Further, how would I go about getting rid of the kernel lib module errors (such as: "modprobe: FATAL: Could not load /lib/modules/2.6.18-4-xen-686/modules.dep: No such file or directory")? My xen domU doesn't have any kernels emerged (no reason to do so since the dom0 takes care of all the kernels). It seems, however, that the kernel the domU is using when booting up wants to see the kernel lib modules inside of the domU xen image. I'm not sure why these errors are there or how to get rid of them.
Any thouhts/ideas greatly appreciated.
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"My downfall raises me to infinite heights." -Napoleon Bonaparte |
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Andre
n00b
Joined: 27 Apr 2002
Posts: 16
Location: Netherlands
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| Posted: Sat Feb 23, 2008 8:48 am Post subject: |
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Don't know about the /proc filesystem, I found this post looking for an answer to the modprobe: FATAL error. The answer is quite simple. The error message itself says what is missing. It cannot find the directory it wants to write the modules.dep file (or initially a temp file) into. just create the missing directories (big chance that /lib/modules does not even exist because you never installed a kernel inside the VM). Here's how I solved it:
| Code: |
xclient ~ # depmod -a
WARNING: Couldn't open directory /lib/modules/2.6.20-xen-r6: No such file or directory
FATAL: Could not open /lib/modules/2.6.20-xen-r6/modules.dep.temp for writing: No such file or directory
xclient ~ # mkdir /lib/modules/2.6.20-xen-r6/
mkdir: cannot create directory `/lib/modules/2.6.20-xen-r6/': No such file or directory
xclient ~ # mkdir -p /lib/modules/2.6.20-xen-r6/
xclient ~ # depmod -a
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Replace the kernel version with your own version, mkdir -p makes sure that missing parent directories are also created. |
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