From: Robert Hancock <hancockrwd@gmail.com>
To: netdev <netdev@vger.kernel.org>
Cc: Francois Romieu <romieu@fr.zoreil.com>
Subject: r8169 64-bit DMA support
Date: Sun, 20 Sep 2009 17:38:20 -0600 [thread overview]
Message-ID: <4AB6BCEC.3070001@gmail.com> (raw)
The r8169 driver currently disables 64-bit DMA support by default (needs
a module parameter to turn it on). This is a bit sub-optimal these days
with most new systems using more than 4GB of RAM. It was this patch back
in 2004 that disabled it:
http://git.kernel.org/?p=linux/kernel/git/torvalds/old-2.6-bkcvs.git;a=commitdiff;h=c525e7cf69bfe18a1bf362558be5398e0b925d07
It's not clear (from the mails I've read) exactly what was going on in
the case that caused this to be added. Normally these days the PCI
subsystem is supposed to detect that DAC isn't usable on a machine and
refuse setting 64-bit DMA masks, it's not the driver's responsibility to
handle this. I'm guessing that when this change was made that detection
didn't exist though.
Thoughts on whether this default can be changed now? Or at least for the
PCI Express devices, which really should have nothing special about
64-bit addressing..
next reply other threads:[~2009-09-20 23:38 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-20 23:38 Robert Hancock [this message]
2009-09-22 11:53 ` r8169 64-bit DMA support Francois Romieu
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