Messages in this thread | | | Subject | Re: Regarding tx-nocache-copy in the Sheevaplug | From | Eric Dumazet <> | Date | Wed, 15 Oct 2014 15:45:27 -0700 |
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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.
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