Re: [PATCH] net: Add back alignment for size for __alloc_skb

From: Tony Lindgren
Date: Wed Nov 02 2011 - 19:19:24 EST


* David Miller <davem@xxxxxxxxxxxxx> [111102 15:42]:
> c>
> > The issue is calculation of skb->end, which is based upon calculated
> > 'size' variable.
> >
> > skb->end determines alignment of skb_shared_info, which is where the
> > alignment problem is occuring for Tony.
>
> Right, and SMP_CACHE_BYTES setting should save us in any case.
>
> For ARM, SMP_CACHE_BYTES seems to be set to L1_CACHE_BYTES which in
> turn is set via ARM_L1_CACHE_SHIFT which can be set seemingly to any
> value but the defaults are 5 and 6 which should be OK.
>
> So unless Tony is using a non-standard setting of ARM_L1_CACHE_SHIFT,
> this report is a bit mysterious.

This is happening at least with omap1_defconfig. In that case we have
ARM_L1_CACHE_SHIFT=5.

Regards,

Tony
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