Aha. So the article is saying that full IOMMU support is waiting on all
AMD64 machines (so that would mean any Intel and AMD-manufactured
processor with VT-d etc.), and you're saying that this is what needs to
be implemented for the buffer cache to finally get >32bit/>~3GB support?
Are there plans today to implement this and then get the >32bit/>~3GB
support going?
(I don't understand exactly how these things fit together, this is why I
asked tentatively.)
Thanks, Tinker
On 2016-02-14 02:03, Karel Gardas wrote:
I'm afraid you read too quickly and w/o attention to detail, please
reread and pay special attention to the last paragraph. Especially to:
"IOMMU is present in all "real" AMD64 machines, but not the Intel
clones. Unfortunately, OpenBSD support for IOMMU on the AMD machines
is not quite ready for primetime (code exists, but "real life" has
consorted against me finishing it)."
On Sat, Feb 13, 2016 at 7:35 PM, Tinker <ti...@openmailbox.org> wrote:
Dear Karel,
Thanks - wait - this post from 2006 you mentioned now, is it saying
that
actually >32bit/>~3GB buffer cache IS SUPPORTED/WORKS on any AMD64
*with
IOMMU* support in the CPU, and was working all the time??
(That would mean that I misunderstood those references I posted in the
previous email because in actuality the 32bit/~3GB constraint only is
in
certain usecases that is on non-IOMMU CPU:s.)
Please clarify!
So if so, any Intel processor with the "Intel® Virtualization
Technology
for
Directed I/O (VT-d)" feature such as for example this one
http://ark.intel.com/products/81061/ , or any of the CPU:s listed on
https://en.wikipedia.org/wiki/List_of_IOMMU-supporting_hardware , has
that
support?
Does the motherboard need specific support too as Wikipedia indicates
-
though at least any Xeon server motherboard from the last 3-4 years
must
for
sure have it right?
Thank you everyone for your excellent work with OpenBSD!
Best regards,
Tinker
[1]
David Mazieres linked to two docs in there, those are only on
archive.org
now:
https://web.archive.org/web/20150814051509/http://www.intel.com/content/dam/w
ww/public/us/en/documents/product-specifications/vt-directed-io-spec.pdf
https://web.archive.org/web/20081218031805/http://www.amd.com/us-en/assets/co
ntent_type/white_papers_and_tech_docs/34434.pdf
On 2016-02-14 01:15, Karel Gardas wrote:
I think you would also like to investigate this one:
http://www.undeadly.org/cgi?action=article&sid=20060614160000
Some quite deep reading [1] taught me that at least quite recently,
there
was a ~3GB cap on the buffer cache, independent of architecture and
system
RAM size.
