Re: [-mm patch] i386: enable 4k stacks by default

Adrian Bunk
2006-01-04T16:58:37Z

On Wed, Jan 04, 2006 at 05:49:25PM +0100, Jesper Juhl wrote:
> On 1/4/06, Adrian Bunk <bunk@stusta.de> wrote:
> > On Wed, Jan 04, 2006 at 05:39:14PM +0100, Jesper Juhl wrote:
> > > On 1/4/06, Adrian Bunk <bunk@stusta.de> wrote:
> > > > This patch enables 4k stacks by default.
> > > >
> > > > 4k stacks have become a well-tested feature used fore a long time in
> > > > Fedora and even in RHEL 4.
> > > >
> > > > There are no known problems in in-kernel code with 4k stacks still
> > > > present after Neil's patch that went into -mm nearly two months ago.
> > > >
> > > > Defaulting to 4k stacks in -mm kernel will give some more testing
> > > > coverage and should show whether there are really no problems left.
> > > >
> > > > Keeping the option for now should make the people happy who want to use
> > > > the experimental -mm kernel but don't trust the well-tested 4k stacks.
> > > >
> > > >
> > > > Signed-off-by: Adrian Bunk <bunk@stusta.de>
> > > >
> > > > --- linux-2.6.15-rc5-mm3-full/arch/i386/Kconfig.debug.old 2006-01-04 11:43:55.000000000 +0100
> > > > +++ linux-2.6.15-rc5-mm3-full/arch/i386/Kconfig.debug 2006-01-04 11:44:14.000000000 +0100
> > > > @@ -53,8 +53,8 @@
> > > > If in doubt, say "N".
> > > >
> > > > config 4KSTACKS
> > > > - bool "Use 4Kb for kernel stacks instead of 8Kb"
> > > > - depends on DEBUG_KERNEL
> > > > + bool "Use 4Kb for kernel stacks instead of 8Kb" if DEBUG_KERNEL
> > >
> > > Why "if DEBUG_KERNEL" ?
> >
> > This is simply the same as before with the defaults inverted.
> >
> I just thought that you wanted to get as much testing in -mm as
> possible while still leaving the old stacksize option for those who
> don't yet trust 4K stacks.

That is what my patch does.

> To get maximum testing making 4KSTACKS default Y and removing the "if
> DEBUG_KERNEL" conditional just seems to me to be the obvious choice...

With my version, we are getting the bigger testing coverage - and
getting a big testing coverage in -mm is what we need if we want to know
whether we have really already fixed all stack problems or whether
there are any left.

cu
Adrian

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