From: Eric Dumazet <eric.dumazet@gmail.com>
To: Benjamin Poirier <benjamin.poirier@gmail.com>
Cc: "Lluís Batlle i Rossell" <viric@viric.name>,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
"Carles Pagès" <page@cubata.homelinux.net>,
linux-arm-kernel@lists.infradead.org
Subject: Re: Regarding tx-nocache-copy in the Sheevaplug
Date: Wed, 15 Oct 2014 15:45:27 -0700 [thread overview]
Message-ID: <1413413127.17186.5.camel@edumazet-glaptop2.roam.corp.google.com> (raw)
In-Reply-To: <20141015215701.GA4109@f1.synalogic.ca>
On Wed, 2014-10-15 at 14:57 -0700, Benjamin Poirier wrote:
> On 2014/10/13 12:52, Lluís Batlle i Rossell wrote:
> > Hello,
> >
> > on the 7th of January 2014 ths patch was applied:
> > https://lkml.org/lkml/2014/1/7/307
> >
> > [PATCH v2] net: Do not enable tx-nocache-copy by default
> >
> > In the Sheevaplug (ARM Feroceon 88FR131 from Marvell) this made packets to be
> > sent corrupted. I think this machine has something special about the cache.
> >
> > Enabling back this tx-nocache-copy (as it used to be before the patch) the
> > transfers work fine again. I think that most people, encountering this problem,
> > completely disable the tx offload instead of enabling back this setting.
> >
> > Is this an ARM kernel problem regarding this platform?
>
> This is odd, only x86 defines ARCH_HAS_NOCACHE_UACCESS. On arm,
> skb_do_copy_data_nocache() should end up using __copy_from_user()
> regardless of tx-nocache-copy.
kmap_atomic()/kunmap_atomic() is missing, so we lack
__cpuc_flush_dcache_area() operations.
next prev parent reply other threads:[~2014-10-15 22:45 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-13 10:52 Regarding tx-nocache-copy in the Sheevaplug Lluís Batlle i Rossell
2014-10-13 12:26 ` Eric Dumazet
2014-10-13 12:32 ` Lluís Batlle i Rossell
2014-10-13 14:21 ` Andrew Lunn
2014-10-13 14:31 ` Lluís Batlle i Rossell
2014-10-13 14:49 ` Eric Dumazet
2014-10-13 15:48 ` Lluís Batlle i Rossell
2014-10-15 21:57 ` Benjamin Poirier
2014-10-15 22:45 ` Eric Dumazet [this message]
2014-10-16 17:34 ` Benjamin Poirier
2014-10-16 17:46 ` Lluís Batlle i Rossell
2014-10-17 20:55 ` Benjamin Poirier
2014-10-16 17:48 ` Eric Dumazet
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