On Monday, November 22, 2010 8:01:34 pm Alan Cox wrote: > On 11/22/2010 1:47 PM, John Baldwin wrote: > > On Monday, November 22, 2010 1:37:45 pm Alan Cox wrote: > >> On Mon, Nov 22, 2010 at 6:59 AM, John Baldwin<[email protected]> wrote: > >> > >>> On Sunday, November 21, 2010 8:05:26 pm Sean Bruno wrote: > >>>> Looks like these HP boxes have the capability to do 44 bit memory > >>>> addressing if configured to do so from the BIOS. > >>>> > >>>> Is anyone interested in any data from that setting? > >>> Does it boot ok? :) The MTRR code should handle that (there is a CPUID > >>> field that tells the OS how many bits are significant). Not sure if there > >>> are any places in the pmap that assume 40 bits, but a test boot is > >>> certainly > >>> worth trying. > >>> > >>> > >> Since we don't boot with 40-bit addressing, I can easily predict the > >> outcome. :-) > >> > >> The trouble with this machine is that the second 128GB of RAM is being > >> placed between 512G and 1T in the physical address space, which is beyond > >> the range of the (current) direct map. So, we take a page fault on the > >> first access to a page in the second 128GB through the direct map. > > Heh, I guess that is what your earlier patch did? Once that patch is > > applied > > I think Sean should just try 44-bit mode if so. > > > > Yes. > > If 44-bit addressing makes the placement of DRAM in the physical address > space any sparser, then we'll again have an insufficiently large direct > map. Also, I fear that we won't be able to allocate the vm_page_array > without enabling VM_PHYSSEG_SPARSE, which itself requires a change in > order to work.
I believe someone has a change for that on amd64 already? -- John Baldwin _______________________________________________ [email protected] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "[email protected]"
