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    SubjectRe: 2G memory split
    On Tue, Jan 10 2006, Ingo Molnar wrote:
    > * Jens Axboe <> wrote:
    > > Hi,
    > >
    > > It does annoy me that any 1G i386 machine will end up with 1/8th of
    > > the memory as highmem. A patch like this one has been used in various
    > > places since the early 2.4 days at least, is there a reason why it
    > > isn't merged yet? Note I just hacked this one up, but similar patches
    > > abound I'm sure. Bugs are mine.
    > yes, i made it totally configurable in 2.4 days: 1:3, 2/2 and 3:1 splits
    > were possible. It was a larger patch to enable all this across x86, but
    > the Kconfig portion was removed a bit later because people _frequently_
    > misconfigured their kernels and then complained about the results.

    How is this different than all other sorts of misconfigurations? As far
    as I can tell, the biggest "problem" for some is if they depend on some
    binary module that will of course break with a different page offset.

    For simplicity, I didn't add more than the 2/2 split, where we could add
    even a 3/1 kernel/user or a 0.5/3.5 (I think sles8 had this).

    > so for now the trivial solution is to change the "C" to "8" in the
    > following line in include/asm-i386/page.h:
    > > #define __PAGE_OFFSET (0xC0000000)
    > instead of editing your .config :-)


    That is what I have been doing, but that requires me to carry this patch
    along with me all the time. So it annoys me!

    I would have posted a simple patch moving it to 0xB0000000 which would
    solve the problem for me as well, but I didn't because I'm sure people
    would be screaming at me...

    > Maybe we could try the Kconfig solution again, but it'll need alot
    > better documentation, dependency on KERNEL_DEBUG and some heavy warnings
    > all around.

    The help text could definitely be improved, it was a 30 second hackup.
    Why would you want to make it depend on DEBUG?

    Jens Axboe

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