linux32 sysctl limits?

[Kostik Belousov]

On Fri, Oct 08, 2010 at 04:12:10PM -0700, Steve Kargl wrote:
> On Sat, Oct 09, 2010 at 01:20:13AM +0300, Kostik Belousov wrote:
> > On Fri, Oct 08, 2010 at 03:17:01PM -0700, Steve Kargl wrote:
> > > 'man linux' does not list or describe the following sysctl
> > > variables.
> > > 
> > > compat.linux32.maxvmem: 0
> > > compat.linux32.maxssiz: 67108864
> > > compat.linux32.maxdsiz: 536870912
> > > 
> > > Are there any limitations with setting these to
> > > say 1G for stack and 4G for data on a system with
> > > 16G of memory?
> > 
> > The linux ABI processes are 32bit, so you cannot reallistically assign
> > 4Gb to maxdsiz. The space between data (bss) end and stack bottom is
> > used for mappings, so it should be kept large enough.
> 
> Does this mean that maxssiz+maxdsiz=3G would allow 
> 1G for mappings?  The only linux app that will be
> running is matlab (and I suppose any children processes
> of matlab).

It has a chance of working. I do not know how much is linux userland
sensitive to the address space layout change.
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