Re: [User-mode-linux-user] compiling uml in uml

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

> Funny thing is that it thinks it's running on an um processor. Or
> something. Another thing that goofs up is that my bash login scripts
> add ~/bin.`uname -m` to my path, which works perfectly fine on
> {i386,sparc,sun4u} machines, but not on any of the virtual machines
> here (quite a few already...)

If you don't like 'um' as your arch, put 'fakearch' on the kernel command 
line.

That will make it assume the underlying arch.

> Now this is of course easy to kludge around, but wouldn't it be saner
> if the uml 'kernel' just returned the name of the host architecture to
> 'uname -m' instead of just 'um'? There's not really supposed to be
> anything that distinguishes this virtual machine from a real i386,
> right? 

I'm open to arguments on this one.  It sort of seems like the right thing to 
do.

It also happens automatically, which contributes to its rightness.  In the 
kernel pool, $ARCH is set to 'um' which causes it to build in arch/um.  $ARCH 
is automatically used to fill in the utsname structure.  I'd have to modify 
the generic kernel in order to change that.

> (Apart from some NFS unmount hangs (which might be in stock
> 2.4.0-test6 too, didn't check) and an occasional kernel panic once a
> day, these virtual machines seem to be working remarkably well.) 

How is a kernel panic once a day working remarkably well?  And why don't you 
tell me when it panics?  I can't fix things unless I know about them.  And 
until now, I didn't know about any extant panics.

So, what is the panic, and what's the backtrace, and do you know how to 
reproduce it?

> When trying to load the ip_tables module in an uml I get:
> [root@dev0 netfilter]# insmod ./ip_tables.o 
> ./ip_tables.o: unresolved symbol get_fault_addr 
> ./ip_tables.o: unresolved symbol set_fault_addr
> ./ip_tables.o: unresolved symbol current_task 

They just haven't been exported yet.  Stick EXPORT_SYMBOL in the appropriate 
places, and it should work.  Then send me the patch.

				Jeff