Re: [Xen-devel] [PATCH] x86/setup: do not relocate below the end of current Xen image placement

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 27.11.17 at 20:54, <konrad.wilk@xxxxxxxxxx> wrote:
>     If the user decides to put the kexec crashkernel in the same
>     area (so at the end of the E820_RAM) the relocation routines
>     go haywire. For example with " crashkernel=512M@3327M"
>     
>     we would be usurping the end of the E820_RAM.

I'm tempted to say "just don't do that then", except I realize it may
not be fully predictable where Xen wants to put itself, or the location
may change with a Xen or firmware update.

>     This code doesn't actually fix the underlaying issue
>     with the relocation routines (See below for explanation).

But that's what a proper patch should do.

>     The code assumes that the "new" relocation physical is always
>     going to _after_ where GRUB has put the initial code.
>     
>     In other words - we always move it upwards in memory. But in this case
>     there is no space (because kexec has grabbed it all) so we must move it
>     downward (below where GRUB put us).

As Daniel's patch description says - we shouldn't move Xen at all
in such a case, rather than moving it downwards.

Jan


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