Re: upwards growing stacks ??

Matthew Wilcox (Matthew.Wilcox@genedata.com)
Mon, 4 Oct 1999 09:52:20 +0200


On Sun, Oct 03, 1999 at 10:12:17PM -0500, Linas Vepstas wrote:
> I've been porting the kernel to the ESA/390 architecture (mainframe)
> and have had the occasion to rethink the subroutine linkage. In particular,
> I have some weak reasons to want the stack to grow up, not down. However,
> the unix tradition & linux in particular usually have the stack grow down.
> So the questions:
>
> -- is it a bad idea to make the stack grow up?
> -- has anyone done this before w/ linux? (doesn't seem like it ...)

Some people are doing this right now with Linux/PARISC. The only thing
which affected me was in fs/binfmt_*.c where we tamper with the argc
/ envp. Alan tells me the mklinux people have sorted this one properly,
but I haven't looked yet. There are probably other places where there are
problems. Philipp?

> -- should I do this, or should I stick to the traditional design?

It's something which we need to fix for PARISC, so I think you should
do it too :-)

> -- I'm making the following mods, will these be sufficient?
> Are they appropriate?
> o the expand_stack() inline in include/linux/mm.h assumes the
> stack grows down, & I will rework it to suit my needs ...
> o change VM_STACK_FLAGS to grow up as well ...
> o create a new vma that holds the stack base, out in high-memory,
> somewhere near TASK_SIZE - current->rlim[RLIMIT_STACK].rlim_cur

-- 
Matthew Wilcox <willy@bofh.ai>
"Windows and MacOS are products, contrived by engineers in the service of
specific companies. Unix, by contrast, is not so much a product as it is a
painstakingly compiled oral history of the hacker subculture." - N Stephenson

- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/