-----Original Message----- From: Jed Carlson [mailto:jcarlson@katalix.com] Sent: Wednesday, May 14, 2003 3:44 PM To: linux-net@vger.kernel.org Subject: Re: skbuff headroom guarantee in the driver?
Have you considered whether you can use skb->cb[]? This can be used as a scratch area to pass information with the skb. But be aware that its contents isn't guaranteed to be preserved as the skb passes through the kernel since it may be used by other kernel subsystems. Take a look at how it's used by the TCP code via the macro TCP_SKB_CB().
-Jed
Is there a way to guarantee headroom for the Tx packets to be used in the Mac driver. Increasing the hard_header_len doesn't seem to be the way to go because in the TCP processing skbuffs are allocated with MAX_HEADER_LEN and it doesn't seem appropriate to bank on this macro. If I want to pass some extra information (say, some descriptor realted) to the MAC by prepending the packet, what is the best way to do it? I guess, one could argue that it is no longer a true ethernet header and hence a new header should be introduced. However, the extra information is not any mutated mac header but is some descriptor information that needs to be passed with packet for performance reasons. Needless to say, I'm hoping to avoid using skb_realloc_header in the driver.
- : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
_________________________________________________________________
The new MSN 8: smart spam protection and 2 months FREE* http://join.msn.com/?page=features/junkmail
- : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
