[User-mode-linux-devel] Re: 2.3.51 Networking *smile*

[Jeff D. <jd...@ka...>]

> ifconfig umn down
> 	successfully returns to the command prompt, but promptly hangs uml
> with a: umn_read had error, errno = 9
> 	on the console and the idle thread at 99% on the host. 

I've seen this on shutting down, but it didn't hang anything.  I'll have a 
closer look at it.

> ifconfig umn 172.20.0.244 pointopoint 172.20.0.253
> 	From which the uml-kernel could extract the pointopoint address and
> execute

> um_ifconfig sl0 172.20.0.253 pointopoint 172.20.0.244 

I'll look through the networking code again, but when I wrote the driver, my 
impression was that the only way to give the driver an address was in the 
hardware address, which is why I sneak the IP address in via the ethernet 
address.

What I'm going to do about this is add a command line arg like
	umn0=172.20.0.253

That will let you specify both ends of the slip device (the other is in the 
ifconfig command at boot time).

> 	I suppose Nirvanha would be to have sl0 on the host be able to talk
> to multiple UML's on a simulated ethernet cable: 
> host OS sl0: 192.168.12.1/24 
> uml1 umn:	192.168.12.2/24, default route ->1 
> uml2 umn:	192.168.12.3/24, default route ->1 
> uml3 umn:	192.168.12.4/24, default route ->1 

You're more of a network weenie than I, but I thought that slip devices are 
ptp, so each one has two end, and only one machine at each end.  My plan for a 
virtual net has been to use the host machine as a virtual hub rather than as a 
virtual ethernet.  There would be a slip device for each uml, and the host 
machine would be routing packets between them.  And for a truly virtual net, 
I'm planning on a second driver which just uses normal pipes for umls to talk 
directly to each other without routing through the host.

> How many fhd's are supported?  It looks like MAX_DEV is set to 8 in
> the uml patch.

Is that not enough for you?

> Do they support partition tables so one might actually mount an entire
> physical hard drive via fhd:
> ./linux fhd1=/dev/hdc
> 	where /dev/hdc is a partitioned ide drive?

What good would this be?  The host OS already splits the partitions up and 
makes them available individually.

> BTW - what do you think of the term Virtual Block Device as opposed to
> Fake Hard Disk.  The former makes me think that I could map vbda=/dev/
> hdc vbdb=/dev/ndb1 /vbdc=/dev/sr0 /vbdd=/dev/fd1 - anything that is a
> block device, whereas fhd sounds like it can only be a hard disk.

I like that.  I'll switch at some point.

> Unimplemented syscall : 8
>                          Untested (20092) [0x10171428]: syscall_kern.c
> line 696

> 	From unistd.h: #define __NR_creat                8 

OK, I'll toss that in as well.

> Then start filling up ram with bash's.  Around 312K free, the xterm
> with the bashs and the xterm with top freeze, but the console still
> accepts keystrokes:
> usermode:~# 
> usermode:~# ps axf | less 
Kernel panic: No vma in segv

I run with swap all the time, but I haven't actually forced it to swap in a 
while.  I'll check this out.

> Jeff - could this make its way into cvs, the downloads section (in
> text and html format; I'd be happy to provide a tar with all three if
> that's useful), and into the debian root_fs package on next release
> (it's still at 0.0.4)?

I forgot to rebuild the text versions of the HOWTO when I redid the packages.  
Next time... :-)  Your last changes are available in all their glory in the 
html version on the web site...

				Jeff