Re: Infrastructure for zerocopy I/O

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By the way QNAP NAS systems are shipped with a 64bit kernel but a
32bit system environment.
Those systems support USB 2.0 and USB 3.0.

You can expect any kind of combination out there.


On Wed, Nov 18, 2015 at 7:23 PM, Bjørn Mork <bjorn@xxxxxxx> wrote:
> "Steinar H. Gunderson" <sgunderson@xxxxxxxxxxx> writes:
>> On Tue, Nov 17, 2015 at 03:16:55PM -0500, Alan Stern wrote:
>>> xHCI always uses 64-bit addresses.  But many EHCI controllers don't,
>>> and only a few of the EHCI platform drivers support 64-bit DMA.
>>
>> OK, sure. But are systems with USB2 only and more than 4GB of RAM common?
>
> Hmpff. They are common in my house at least :)
>
> bjorn@nemi:~$ lspci -nn|grep USB
> 00:1a.0 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 [8086:2937] (rev 03)
> 00:1a.1 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 [8086:2938] (rev 03)
> 00:1a.2 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 [8086:2939] (rev 03)
> 00:1a.7 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 [8086:293c] (rev 03)
> 00:1d.0 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 [8086:2934] (rev 03)
> 00:1d.1 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 [8086:2935] (rev 03)
> 00:1d.2 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 [8086:2936] (rev 03)
> 00:1d.7 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 [8086:293a] (rev 03)
> bjorn@nemi:~$ grep MemTotal /proc/meminfo
> MemTotal:        8051536 kB
>
> bjorn@canardo:~$ lspci -nn|grep USB
> 00:1a.0 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #4 [8086:2937] (rev 02)
> 00:1a.1 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #5 [8086:2938] (rev 02)
> 00:1a.2 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #6 [8086:2939] (rev 02)
> 00:1a.7 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #2 [8086:293c] (rev 02)
> 00:1d.0 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #1 [8086:2934] (rev 02)
> 00:1d.1 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #2 [8086:2935] (rev 02)
> 00:1d.2 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB UHCI Controller #3 [8086:2936] (rev 02)
> 00:1d.7 USB controller [0c03]: Intel Corporation 82801I (ICH9 Family) USB2 EHCI Controller #1 [8086:293a] (rev 02)
> bjorn@canardo:~$ grep MemTotal /proc/meminfo
> MemTotal:        8195224 kB
>
> Most systems of that generation can take 8GB RAM, and there isn't really
> any reason not to max that out, is there?
>
>> (And will they not increasingly die out, if nothing else as USB3 becomes
>> commonplace?)
>
> Can you wait 10 years for that to happen, or do you want a solution
> earlier?
>
>
> Bjørn
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