Date: Mon, 22 Nov 2010 14:47:12 -0500 From: John Baldwin <jhb@freebsd.org> To: alc@freebsd.org Cc: freebsd-current@freebsd.org, Sean Bruno <seanbru@yahoo-inc.com> Subject: Re: 40 vs 44 bit memory addressing HP DL580/980 Message-ID: <201011221447.13026.jhb@freebsd.org> In-Reply-To: <AANLkTi=-t7TYM7ydtV_KktozsvUHv%2BA%2B=PvAjTn1mDq-@mail.gmail.com> References: <1290387926.16558.1283.camel@home-yahoo> <201011220759.16082.jhb@freebsd.org> <AANLkTi=-t7TYM7ydtV_KktozsvUHv%2BA%2B=PvAjTn1mDq-@mail.gmail.com>
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On Monday, November 22, 2010 1:37:45 pm Alan Cox wrote: > On Mon, Nov 22, 2010 at 6:59 AM, John Baldwin <jhb@freebsd.org> 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. -- John Baldwin
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