On Thu, 2015-10-22 at 13:53 +0200, Helge Deller wrote:
> > > Betreff: [PATCH v3] parisc: Change L1_CACHE_BYTES to 16
> > > The latest version changes L1_CACHE_BYTES to 16 bytes and doesn't adjust SMP_CACHE_BYTES as
> > > per James suggestion
> >
> > This patch sadly breaks build on Linux kernel git head:
> >
> > In file included from /home/cvs/LINUX/git-kernel/linux-2.6/net/core/dev.c:92:0:
> > /net/core/dev.c: In function ‘expand_xps_map’:
> > /include/linux/netdevice.h:721:27: warning: overflow in implicit constant conversion [-Woverflow]
> > #define XPS_MIN_MAP_ALLOC ((L1_CACHE_BYTES - sizeof(struct xps_map)) \
> > /net/core/dev.c:1972:18: note: in expansion of macro ‘XPS_MIN_MAP_ALLOC’
> > int alloc_len = XPS_MIN_MAP_ALLOC;
>
> This is one possibility to fix it:
>
> diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
> index 2d15e38..21cf683 100644
> --- a/include/linux/netdevice.h
> +++ b/include/linux/netdevice.h
> @@ -718,7 +718,7 @@ struct xps_map {
> u16 queues[0];
> };
> #define XPS_MAP_SIZE(_num) (sizeof(struct xps_map) + ((_num) * sizeof(u16)))
> -#define XPS_MIN_MAP_ALLOC ((L1_CACHE_BYTES - sizeof(struct xps_map)) \
> +#define XPS_MIN_MAP_ALLOC ( (L1_CACHE_BYTES > sizeof(struct xps_map) ? L1_CACHE_BYTES : 2 * L1_CACHE_BYTES) - sizeof(struct xps_map) \
> / sizeof(u16))
But it indicates the whole kernel has the architectural assumption that
L1_CACHE_BYTES >= 32, so I don't think we should be trying to change
that.
James
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