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    SubjectRe: [Fastboot] [PATCH 1/1] Allow i386 crash kernels to handle x86_64 dumps
    On Fri, Mar 16, 2007 at 08:52:30AM +0530, Vivek Goyal wrote:
    > On Fri, Mar 16, 2007 at 11:40:07AM +0900, Magnus Damm wrote:
    > > On 3/16/07, Horms <horms@verge.net.au> wrote:
    > > >On Thu, Mar 15, 2007 at 06:56:16PM +0530, Vivek Goyal wrote:
    > > >> On Thu, Mar 15, 2007 at 12:22:57PM +0000, Ian Campbell wrote:
    > > >> > On Thu, 2007-03-15 at 11:17 +0530, Vivek Goyal wrote:
    > > >> > > > > But I think changing this macro might run into issues. It is
    > > >> > > > > being used at few places in kernel, for example while loading
    > > >> > > > > module. This will essentially mean that we allow loading 64bit
    > > >> > > > > x86_64 modules on 32bit i386 systems?
    > > >> >
    > > >> > Yes, not sure how I missed that fact...
    > > >> >
    > > >> > > Kexec will also not allow loading an x86_64 kernel on a 32bit
    > > >machine.
    > > >> >
    > > >> > For crash kernel only or for regular kexec too?
    > > >> >
    > > >>
    > > >> I think for both. One of the possible reasons I think is that one never
    > > >> knows is underlying machine has got 64bit extensions or not. So even if
    > > >> we load the kernel it will never boot. Secondly, we might not be able to
    > > >> handle 64bit address in 32bit kernel/user space?
    > > >
    > > >Perhaps I am miss-understanding what you are saying, but I do
    > > >recally kexecing from 32->64 and 64->32 bit kernels on x86_64 hardware.
    > > >I can run these checks again if it helps.
    > >
    >
    > I stand corrected. I can kexec an bzImage 32->64bit. That's a different
    > thing that it ran into some initrd issues later but fundamentally kexec
    > could load 64bit kernel bzImage and do the successful transition.
    >
    > So it will now be left to the user. If he tries to kexec to a 64bit kernel
    > on a machine not supporting 32bit extensions, then kexec will not give
    > any advance warning.

    I feel comfortable with that. Well for now anyway.
    But I think that Magnus has other ideas.

    --
    Horms
    H: http://www.vergenet.net/~horms/
    W: http://www.valinux.co.jp/en/

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