Re: [9fans] lguest port broken due to some change in last 6 months; any ideas?

[John Soros <sorosj@gmail.com>]

Hi,
I have tried to run the lguest port on a 2.6.25 kernel, with not much luck. I guess i was successful in setting the thing up, as

> There were a number of changes in the kernel last 6 months, I just
> recently did a pull and the lguest port is screwed. I spent part of
> today fixing things and catching up, and am now stuck in the first
> taskswitch.
>
> Symptoms are odd. It dies in the first call to gotolabel.
>
> But here is the output from some prints:
> mmuswitch done return to 0xc01508de
> port/proc.c goto label c0470008 (pc c01013b3, sp c0059778)
>
> That pc is init0; the SP is good, previously allocated in newproc().
> Next line after this is from lguest program. Lguest says this:
> lguest: Bad address 0xc0012c01 (gpte 01008200)
my  kernel dies with the same error, different address though. The kernel starts:
"hello squidboymach0init"
then it finds a console, echo's to it:
"Found a console! try output!
============================== hi there ========================"
but then the last few lines are:
"lgv reset done
findlgv net0, @2
Config: 0: 0x0 0xff 0x6 0x1d 0x1 0xd7
found one enet ctlr
Jiggering address
#l0: lg: 10lguest: bad read address 0xc0012044 len 4"
looks very much like the error you described.
Is there any outlook for this to be fixed, i would be really happy to be able to have a plan9 cpu server and whatnot on my machine.
9vx doesn't work for me for this reason.

>
> The gpte is the pte that the lguest kernel code found for that address.
>
> eh? c0012c01? It makes not a lot of sense, that's not word aligned, as
> it should be for accesses to cpu0pdb.
> And ... it dies in gotolabel here:
> TEXT gotolabel(SB), $1
> 	MOVL	label+0(FP), AX
> 	MOVL	0(AX), SP			/* restore sp */
> 	MOVL	4(AX), AX			/* put return pc on the stack */
> 	MOVL	AX, 0(SP)
> 	MOVL	$1, AX				/* return 1 */
> DIE DIE DIE
> 	RET
>
> as determined by me putting calls to lguest crash, line by line. Yep,
> it dies on an immediate move to AX.
>
> I'm thinking I'm overwriting code somehow. Anybody has ideas on how to
> debug this, let me know. I've had lots of weird problems on these
> lguest ports but this one takes the cake.
>
> oh yeah I have fixed the port with the new bits in memory.c, l.s, etc.
> for handling 8 MB of initial mappings.
>
> ron
>

Thanks,
John