[Umlbuilder-devel] UML Builder futures

[Roger B. <ro...@ro...>]

[I edited the order of your questions/points]

> I'm stunned,
> actually, by how fast the Redhat 7.2 installation runs, compared with that
> ancient Debian image from UML's SourceForge files page.

I've noticed the same thing on real hardware.  The new Linux distributions
are getting faster.  (I assume compiling against i586/i686 is helping
amongst other things).

> Roger, where are you looking at taking UMLBuilder? 

Ideally I would like it to be come obsolete because UML would just run
the native installers, and everything would "just work".  (Ok, so that
would never happen :-)

More detailed answer at the end.

> Some things I think would be cool are:
> 
> * Create persistent tun devices on host, so users running UML don't have the
> ability to grab IPs through setuid uml_helper.

I want to solve this a different way.  I would like there to be a file
in /etc that lists what ip addresses a user can have, which uml_net 
enforces.  This way minimal admin maintenance is required.  (It would
be in a similar style to tcp wrappers).

I am going to do this as a patch to UML soon (once I get back from a 
well earned holiday over the next two weeks).

> * Attach ttys to host's IP ports over sshd, so startup and running of UMLs
> is effectively silent.

Good idea.  FR# 543170

> * In conjunction with the above, an addition to control script that directs
> stdout to a logfile?

FR# 543171

> * Ext3 support.

It actually already does.  Add 'ext3' to the 'supportedfs' list in the profile.

I generally take the attitude that I only "support" what is in the standard
UML RPM produced by Jeff.  This is because any user who is capable of recompiling
UML to fit their needs is also capable of making their own highly customised
filesystems.

ext3 was only recently added to UML.  The testing effort is large for each
"feature" I turn on, so they lag a bit.  (I actually added ext3 a long time
ago, but didn't test it).

(The testing is fun.  There is an automatic test generator script that grovels
through my collection of rpms and does the installation.  I then have to dig
through all the log files to ensure it went ok.  Finally I have to run each
one and login, scrutinise start messages etc.  A single tweak in the main
code then requires this whole process again, as some distributions are very
temperamental about installation order, files/directories that already exist,
contents of /proc etc).

> * An ability to add "basic utils" to base install, like ftp, ncftp, wget,
> lynx, lsof, emacs-nox, sshd, etc.

Everyone's definition of "basic utils" differs though.  I figure this will
be covered by 505686.

> * Creation of a tmpfs tmp directory under the user's home directory for use
> by each UML.
> A couple of questions: I run my RH7.2 UML with mem=64M. I noticed that about
> that amount is taken up in /tmp now. How does that work? Do I need my tmpfs
> to be the size of all my UMLs' cumulative mem= parameters?

I believe Jeff is doing work in this area.  At the moment, memory is consumed
from tmpfs as you observed.

> Also, I noticed it sets the tun device to the same IP as the host. I thought
> I read it was supposed to be different from the host IP. Has that changed,
> or did I read wrong? And does this mean I can just make as many UMLs as I
> like, with them all pointed to that one tun device?

It works as I ship it.  The endpoint inside your UML session needs to be
different, but the endpoint on the host doesn't have to be unique.  The UML
docs show it being different.

It was a great relief when I originally worked on this since I really didn't
want to allocate two IPs for UML session.

> I've seen your ToDo list,
> obviously, but I'm curious what your long-term goals look like.

Short/medium term I want to make it do more of "the right thing".

- Improved user interface, including allowing changes after installation
  (eg changing the size and type of a filesystem, IP address etc)
- Make existing features of UML easier to use (for example "undoable"
  filesystems using cow)
- Cope with upgrades of UML itself (install new modules, generate new
  initrd)

Longer term I want to make it complement UML features.  For example I
anticipate that UML will eventually have the ability to save its memory
out so that you can "suspend" a session.  UML Builder can provide a
nice easy to use interface to that sort of thing.

Roger