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

    Sam


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