efx_start_datapath() asserts that we can fit 2 RX scatter buffers plus a software structure, each cache-aligned, into a single page. Where L1_CACHE_BYTES == 256 and PAGE_SIZE == 4096, which is the case on s390, this assertion fails. Reduce EFX_RX_USR_BUF_SIZE to make this work. This should also be good for performance, as it ensures that each RX scatter buffer covers whole cache lines and slightly reduces the use of DMA writes that can require a read-modify-write on inter-processor links. (We could use 2048 - L1_CACHE_BYTES, but EFX_RX_USR_BUF_SIZE also affects user-level networking where a larger amount of housekeeping data may be needed. Although this version of the driver does not support user-level networking, I prefer to keep scattering behaviour consistent with the out-of-tree version.) Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> Reported-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx> Signed-off-by: Ben Hutchings <bhutchings@xxxxxxxxxxxxxx> --- Heiko or Geert, please confirm that this really does fix the build failure - I don't have an s390 toolchain. Ben. drivers/net/ethernet/sfc/net_driver.h | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/sfc/net_driver.h b/drivers/net/ethernet/sfc/net_driver.h index 9bd433a..6c8e1a8 100644 --- a/drivers/net/ethernet/sfc/net_driver.h +++ b/drivers/net/ethernet/sfc/net_driver.h @@ -72,8 +72,10 @@ /* Maximum possible MTU the driver supports */ #define EFX_MAX_MTU (9 * 1024) -/* Size of an RX scatter buffer. Small enough to pack 2 into a 4K page. */ -#define EFX_RX_USR_BUF_SIZE 1824 +/* Size of an RX scatter buffer. Small enough to pack 2 into a 4K page, + * and should be a multiple of the cache line size. + */ +#define EFX_RX_USR_BUF_SIZE (2048 - 256) /* Forward declare Precision Time Protocol (PTP) support structure. */ struct efx_ptp_data; -- Ben Hutchings, Staff Engineer, Solarflare Not speaking for my employer; that's the marketing department's job. They asked us to note that Solarflare product names are trademarked. -- To unsubscribe from this list: send the line "unsubscribe linux-s390" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
