On 12/27/2010 04:06 PM, Vivek Goyal wrote: > On Mon, Dec 27, 2010 at 12:31:20PM -0800, H. Peter Anvin wrote: >> Hi guys, >> >> I'm planning a major overhaul of the trampoline allocation in x86, and >> I'm trying to understand how kdump deals with it. The trampoline has to >> be allocated in low memory (< 1 MiB) and obviously that doesn't include >> the kdump area at all. > > Hi Peter, > > Kdump has the concept of backup area. We backup the contents of first > 640KB of physical RAM in kdump reserved area and then allow kdump kernel > to use first 640KB of memory. So any trampoline allocation can be done > in low memory area without overwritting the contents of first kernel. > OK, that's straightforward. That presumably means that the low 640K is marked unused in the memory map that memblock sees during early startup. That fits very cleanly with the patches I'm doing. Thanks! -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
