[uml-devel] Re: UML and valgrind

["D. Bahi" <dbahi@enterasys.com>]

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cc'ing valgrind users to solicit support!

as of valgrind 2.1.2 is happy as can be within a User Mode
Linux hosted session. This was tested with 2.4.24-1um and
2.4.26-2um + incrementals on a RedHat 9 (non-nptl, skas)
host - and using RH9 UML filesystems.

still trouble with launching a UML itself under valgrind
(even with MODE_SKAS, ! MODE_TT, and KERNEL_STACK_ORDER=3)

for starters we have:

[u2](dbahi)443$ ~/valgrind-2.1.2/bin/valgrind --tool=memcheck 
/local/dbahi/kernels/linux-2.4.26_uml-patch-2.4.26-2um/linux umid=kickme 
ubd0=/local/cow/kickmoo,/local/dbahi/root_fs.rh-9-full 
ubd1=/local/cow/kickmoo2,/local/dbahi/swap_fs.256 
hostfs=/local/hostfs/kickdir/

Executable is mapped outside of range (nil)-0x52c00000
valgrind: 
do_exec(/local/dbahi/kernels/linux-2.4.26_uml-patch-2.4.26-2um/linux) 
failed: Cannot allocate memory

How does one get around this sudden valgrind exit?

Bahi, David wrote:

> back some time ago it seems like someone had more than a clue as to what
> was requried to get valgrind working under UML... well as of 2.1.1 it
> still ain't working.
> 
> http://marc.theaimsgroup.com/?l=user-mode-linux-devel&m=107066894230633&
> w=2
> 
> I was wondering if a patch was available for our 'community' to make use
> of this tool... for both running the UML as an application and for
> running
> applications within the UML.
> 
> It seems that for running valgrind within the UML there is a signal
> handling
> problem where 'restorer' is NULL and causes a panic in
> setup_signal_stack_si
> 
> signal_kernel.c
>   handle_signal()
> 
> 	if (ka->sa.sa_flags & SA_RESTORER) restorer =
> ka->sa.sa_restorer;
> 	else restorer = NULL;
> 
> 	if(ka->sa.sa_flags & SA_SIGINFO)
> 		err = setup_signal_stack_si(sp, signr, (unsigned long)
> handler,
> 					    restorer, regs, info,
> &save);
> 
> thanks for any insight.
> 
> db
> 
> "The kernel is the only UNIX code that cannot be substituted by a user
> to his own liking. For this reason, the kernel should make as few real
> decisions as possible." -- K. Thompson

-- 
There are two kinds of people in this world: Those that enter a room and 
turn the television set on, and those that enter a room and turn the 
television set off. -- Raymond Shaw, The Manchurian Candidate (1962).

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