"H. Peter Anvin" <hpa at zytor.com> writes: > On 08/11/2010 02:51 PM, Eric W. Biederman wrote: >> >> 3) I would start just getting the normal kexec case to work. >> The 64bit kernel does support starting at the 64bit entry point, >> but I don't think it has been tested if loaded above 4G. >> > > I can guarantee that it hasn't; I looked at that code not all that long > ago and it's shock-full of 32- and 39-bit assumptions. Ugh. I thought I had purged the 32bit assumptions. I guess it has been a while. 39-bit assumptions are forgivable, the architecture didn't support more than 40bit physical addresses when it was written. I wonder if this is a problem for SGI. I remember on the ia64 NUMA machines only node 0 had memory below 4GiB and so if you booted without node 0 you had no memory below 4GiB. I wonder if this restriction has carried over to the x86_64 descendants of the Altix. What is definitely true (unless someone has added an extension since last I looked ) is that on a normal x86 smp architecture you can't start additional processors without memory in the low 1MiB because that is all you can specify in the startup ipi. Eric
