Question regardin intel64 arch and page table setup
Eric W. Biederman
ebiederm at xmission.com
Wed Aug 11 20:22:49 EDT 2010
"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.
More information about the kexec