Subject: Re: [PATCH RFCv2 bpf-next 00/18] XDP-hints: XDP gaining access to HW offload hints via BTF

From: Jakub Kicinski <[email-masked]>
Date: Tue, 4 Oct 2022 17:59:52 -0700

On Tue, 4 Oct 2022 17:25:51 -0700 Martin KaFai Lau wrote:
> A intentionally wild question, what does it take for the driver to return the 
> hints.  Is the rx_desc and rx_queue enough?  When the xdp prog is calling a 
> kfunc/bpf-helper, like 'hwtstamp = bpf_xdp_get_hwtstamp()', can the driver 
> replace it with some inline bpf code (like how the inline code is generated for 
> the map_lookup helper).  The xdp prog can then store the hwstamp in the meta 
> area in any layout it wants.

Since you mentioned it... FWIW that was always my preference rather than
the BTF magic :)  The jited image would have to be per-driver like we
do for BPF offload but that's easy to do from the technical
perspective (I doubt many deployments bind the same prog to multiple
HW devices)..