Re: [Valgrind-users] How to mark separate bits as undefined?

[Azat K. <a3a...@gm...>]

On Wed, Apr 08, 2015 at 08:43:27AM +0300, juris wrote:
> Hello, I was wondering if it is possible to partially mark
> a memory location as undefined when running under valgrind.
> 
> I am using a custom allocator, that allocates a some bits
> in a bitmap for each memory allocation. I would like to catch
> access to these bits before they are initialized. Is there some
> way to do it?
> 
> Thank you for the help.

You could look at VALGRIND_SET_VBITS here:
http://valgrind.org/docs/manual/mc-manual.html

Example here:
http://repo.or.cz/w/valgrind.git/blob/HEAD:/memcheck/tests/metadata.c