Re: [User-mode-linux-devel] UML/PPC status

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

> Ok.  It's possible that that sequence of ptrace calls may need to be
> separated out, since the PPC stuff may need to set several more
> registers than i386.

I think I mentioned in one of my various pieces of mail that I'm going to 
change it to UM_EXEC_INIT(pid) (I just made up the name right now though...).  
That gives i386 the info it needs.  If ppc needs to zero out a bunch of 
registers, you can define it as
	({ ptrace(PTRACE_POKEUSER, pid, reg1, 0);
	   ptrace(PTRACE_POKEUSER, pid, reg2, 0);
	   ...
	   0; })

> I don't know how much of that is handled by the exec code outside of
> arch/um, and how much is actually supposed to be done by your code.

Any low-level stuff like setting up registers is done in the arch layer.  The 
address space and everything else is set up by the upper layers.

> Incidentally, it looks like the current system I have is falling over
> inside padzero() from the elf loading stuff.  I suppose that means the
> bss hasn't been mapped properly. 

That's supposed to get a segfault.  The fault handler is supposed to map in 
the page properly.  When you exec, there are going to be three segfaults 
before the process actually gets going - the stack, padzero filling out bss, 
and the entry point.  So the segfault handler is going to map those three 
pages in before anything else happens.

				Jeff