Date: Fri, 16 Aug 2013 11:42:44 -0700 From: Neel Natu <neelnatu@gmail.com> To: Chris Torek <chris.torek@gmail.com> Cc: alc@freebsd.org, freebsd-current <freebsd-current@freebsd.org>, Neel Natu <neel@freebsd.org> Subject: Re: expanding past 1 TB on amd64 Message-ID: <CAFgRE9G6yHJV4Pk0WpzEHJHLz2HBQ0Hd3968x94ZtmA_hEimiw@mail.gmail.com> In-Reply-To: <CAPx1GvdSmxnXhF3xvhWLscF2H7Vsns6GL7Ve=w_c7iCeAcKPhA@mail.gmail.com> References: <201306190832.r5J8WZFE082135@elf.torek.net> <CAJUyCcOxJt5DpZmnmzaV%2B57auntFA37maoic8Wa4_KUZsfoZ-g@mail.gmail.com> <CAPx1GvdSmxnXhF3xvhWLscF2H7Vsns6GL7Ve=w_c7iCeAcKPhA@mail.gmail.com>
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Hi Chris, Alan: On Sun, Jul 21, 2013 at 1:19 AM, Chris Torek <chris.torek@gmail.com> wrote: > (Apologies for delay in reply, family issues) > > I'd be fine with 4 TB instead of 16; and, at this point, with the latest > patches, it's easily tuned. The auto-sizing of the direct map is not > affected by sparse space as it keys off Maxmem, which is not actually > physical size, but rather "one past last valid physical page". > Here is the patch that I intend to commit: http://people.freebsd.org/~neel/patches/amd64_pmap_4TB.patch This patch bumps up the direct map to 4TB and the KVA to 2TB. It is identical to the patch you posted on hackers except for changing the limits: http://lists.freebsd.org/pipermail/freebsd-hackers/2013-July/043139.html Tested inside a bhyve virtual machine with a *very* sparse memory layout with a memory segment that cuddles up with the 4TB limit. best Neel > > The direct map limit might not need to be "twice kernel virtual size" but > on Intel memory-controller systems needs to be "greater than KVM size" du= e > to moving DRAM up past the PCI hole. Unless the restriction that the > direct-map area be a power of two size is removed, that winds up meaning > "twice". (Removing the restriction seems easy enough=97instead of "pa | > highbits" to obtain VA and "va &~ highbits" to obtain PA, just use "phys = + > offset" and "virt - offset". I didn't see a reason to bother with the > effort, though.) > > Chris >
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