On 2/8/23 06:08, Jakub Kicinski wrote: > On Tue, 1 Aug 2023 22:26:20 +0800 Leon Hwang wrote: >> When error happens in dev_xdp_attach(), it should have a way to tell >> users the error message like the netlink approach. >> >> To avoid breaking uapi, adding a tracepoint in bpf_xdp_link_attach() is >> an appropriate way to notify users the error message. >> >> Hence, bpf libraries are able to retrieve the error message by this >> tracepoint, and then report the error message to users. > > Whatevered-by: Jakub Kicinski <kuba@xxxxxxxxxx> ? Oh, it's not responsible for libraries to retrieve the error message. It should be users' responsibility. Sorry for the misguiding text. In the previous patch[0], which changes uapi, it's able to back-propagate the error message from dev_xdp_attach() to userspace through BPF syscall. Then, tracepoint idea is suggested to avoid changing uapi. I do agree to implement a tracepoint to avoid changing uapi. [0] bpf: Introduce user log https://lore.kernel.org/bpf/20230708040750.72570-1-hffilwlqm@xxxxxxxxx/ Thanks, Leon
