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SubjectRe: [PATCH 03/14] x86, config: change defaults PHYSICAL_START and PHYSICAL_ALIGN

* Sam Ravnborg <sam@ravnborg.org> wrote:

> On Thu, May 07, 2009 at 03:26:51PM -0700, H. Peter Anvin wrote:
> > From: H. Peter Anvin <hpa@zytor.com>
> >
> > Change the default for CONFIG_PHYSICAL_START to 16 MB; 4 MB if
> > EMBEDDED. Change the default for CONFIG_PHYSICAL_ALIGN to match up
> > with a large page alignment datum (4 MB for non-PAE, 2 MB for PAE.)
> >
> > The default of 16 MB is designed to avoid occupying ZONE_DMA, as well
> > as avoiding a 15-16 MB memory hole, which some vendors inexplicably
> > still have in their systems.
> >
> > [ Impact: minor performance improvement, leave ZONE_DMA free ]
> >
> > Signed-off-by: H. Peter Anvin <hpa@zytor.com>
> > ---
> > arch/x86/Kconfig | 19 +++++++++++--------
> > 1 files changed, 11 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 039c3f0..13b3a5a 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1455,17 +1455,20 @@ config KEXEC_JUMP
> >
> > config PHYSICAL_START
> > hex "Physical address where the kernel is loaded" if (EMBEDDED || CRASH_DUMP)
> > - default "0x1000000" if X86_NUMAQ
> > - default "0x200000" if X86_64
> > - default "0x100000"
> > + default "0x400000" if EMBEDDED
> > + default "0x1000000"
> > ---help---
> > This gives the physical address where the kernel is loaded.
> >
> > If kernel is a not relocatable (CONFIG_RELOCATABLE=n) then
> > bzImage will decompress itself to above physical address and
> > - run from there. Otherwise, bzImage will run from the address where
> > - it has been loaded by the boot loader and will ignore above physical
> > - address.
> > + run from there. Otherwise, bzImage will run from the either
> > + the above physical address or where it has been loaded by
> > + the boot loader, whichever is higher.
> > +
> > + For embedded machines with very small memory (less than
> > + about 24 MB) this may need to be adjusted downward from the
> > + default value of 0x1000000 (16 MB).
>
> But in the above you say that default is "0x400000" if EMBEDDED
> That is in contradiction with the help - no?

Yes, the help text is wrong.

Ingo


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