UML development, anyone?

Hello all,

I'm a long-time UML user and lately I've become a bit worried on the state of the UML. This list, as well as the -user one, is very quiet these days. Is there someone still actively developing the UML? I have to say I really like it! Running Linux on Linux reliably and efficiently, just what I need! :-)

I'm currently running three UML virtual machines on an server using Athlon XP-M. The host is running 2.6.31 and the guests are 2.6.27.

I cannot upgrade neither host nor guests due to these problems:

- SKAS 3 patches available up to 2.6.31 only. Merging this to current kernel might not be a problem, just some work, but:

- Severe data corruption on guest on recent guest kernel versions. I'm using a few hard disk partitions directly for UML guests. Something after 2.6.27 guest breaks this quite badly. Even for small data sets like 100 MiB, copying a file to a different location on guest and then running md5sum on both often produces a different result.

Do I have any options than to switch to Qemu and suffer the performance penalty from emulation (kqemu is obsolete, too) or to switch to newer hardware that supports kvm? Qemu performance is somewhat less than 10 % of the native (or UML) performance.

I also found something called lguest but haven't given it a try yet. Looks the most interesting but that doesn't seem to have much list activity either. So it works perfectly for almost everyone or has few users... ;)

How are others coping in the current situation? Or is it just me who has these troubles...?

Best regards,

Quoted 27 lines · Sakari Ailus

Hello all,

I'm a long-time UML user and lately I've become a bit worried on the state of the UML. This list, as well as the -user one, is very quiet these days. Is there someone still actively developing the UML? I have to say I really like it! Running Linux on Linux reliably and efficiently, just what I need! :-)

I'm currently running three UML virtual machines on an server using Athlon XP-M. The host is running 2.6.31 and the guests are 2.6.27.

I cannot upgrade neither host nor guests due to these problems:

- SKAS 3 patches available up to 2.6.31 only. Merging this to current kernel might not be a problem, just some work, but:

- Severe data corruption on guest on recent guest kernel versions. I'm using a few hard disk partitions directly for UML guests. Something after 2.6.27 guest breaks this quite badly. Even for small data sets like 100 MiB, copying a file to a different location on guest and then running md5sum on both often produces a different result.

Do I have any options than to switch to Qemu and suffer the performance penalty from emulation (kqemu is obsolete, too) or to switch to newer hardware that supports kvm? Qemu performance is somewhat less than 10 % of the native (or UML) performance.

Quoted 8 lines

I also found something called lguest but haven't given it a try yet. Looks the most interesting but that doesn't seem to have much list activity either. So it works perfectly for almost everyone or has few users... ;)

How are others coping in the current situation? Or is it just me who has these troubles...?

I hear you ...

I'm using UML for years, as my developing platform for new Kernel code. You can imagine how it shortens the development cycle. For guests I must use the absolute newest Kernel all the time. So ...

- Please send a detailed bug report about that data corruption so someone can reproduce it. I'm not sure what block device you are using but it has a bug. If you have a good version 2.6.27 and a bad version 2.6.28. It should be easy to "git bisect" to the exact patch that broke the system, and should be easy to fix. (Tell me if you need help, it's easy really)

- I probably don't have your problem because in my UMLs /home is an NFS mount to the office /home server. And any other data intensive work is done over iscsi mounts. Look into iscsi Qemu mangament tools , they should work well for UML as well. (Note you'll need to kconfig scsi and iscsi in your guest compile, they are off by default)
(The general rule is any UML specific drivers tend to rot faster then
any generic driver like iscsi or nfs)

- SKAS 3: haaa SKAS3, that one is abandoned. It will need a maintainer to get it alive again. How much better is it? do you have some numbers. (I never used it, the all point was to keep the desktop (host) with a distro Kernel, nvidia and all that)

Quoted 5 lines

- Please send a detailed bug report about that data corruption so someone can reproduce it. I'm not sure what block device you are using but it has a bug. If you have a good version 2.6.27 and a bad version 2.6.28. It should be easy to "git bisect" to the exact patch that broke the system, and should be easy to fix. (Tell me if you need help, it's easy really)

I did write about this back then but it seems no-one else had the same problem. It's one thing to find it and the other to fix it. My wild guess is that it's not a change to that actual driver that broke it.