On 14 July 2014 18:44, Jonas Gorski <j...@openwrt.org> wrote: > On Mon, Jul 14, 2014 at 6:23 PM, Felix Fietkau <n...@openwrt.org> wrote: >> It looks to me like the hardware is overwriting the skb shared info (at >> the end of the skb data buffer), possibly because the configured maximum >> frame length may be too big for the buffer. >> >> If I were to speculate wildly, I would guess that B44_RXMAXLEN refers to >> the maximum frame length, not the maximum buffer length - and in the >> code, it's being fed with the maximum buffer length. >> This would allow the hardware to receive slightly oversized frames which >> can corrupt the skb. > > Since there is a public datasheet[1], this is easily verifiable, and > it looks you are right: > > "Receive Maximum Length Register (RcvLength, Offset 0x404): > > The value stored in this register specifies the largest valid Ethernet > Frame to be received." > > The same is true for the XmtMaxLength register, which is also set "too > large" (it defaults to 1518).
I wonder what's the point of that register if we set length per-skb anyway (b44_alloc_rx_skb): ctrl = (DESC_CTRL_LEN & RX_PKT_BUF_SZ); _______________________________________________ openwrt-devel mailing list openwrt-devel@lists.openwrt.org https://lists.openwrt.org/cgi-bin/mailman/listinfo/openwrt-devel
