On 12/20/2018 01:24 PM, Quentin Monnet wrote: > Make bpftool able to dump a subset of the parameters collected by > probing the system as a listing of C-style #define macros, so that > external projects can reuse the result of this probing and build > BPF-based project in accordance with the features available on the > system. > > The new "macros" keyword is used to select this output. An additional > "prefix" keyword is added so that users can select a custom prefix for > macro names, in order to avoid any namespace conflict. > > Sample output: > > # bpftool feature probe kernel macros prefix FOO_ > /*** System call availability ***/ > #define FOO_HAVE_BPF_SYSCALL > > /*** eBPF program types ***/ > #define FOO_HAVE_SOCKET_FILTER_PROG_TYPE > #define FOO_HAVE_KPROBE_PROG_TYPE > #define FOO_HAVE_SCHED_CLS_PROG_TYPE > ... > > /*** eBPF map types ***/ > #define FOO_HAVE_HASH_MAP_TYPE > #define FOO_HAVE_ARRAY_MAP_TYPE > #define FOO_HAVE_PROG_ARRAY_MAP_TYPE > ... > > /*** eBPF helper functions ***/ > ... > #define FOO_BPF_SKB_CHANGE_HEAD_HELPER_COMPAT_LIST "" \ > "lwt_xmit " \ > "sk_skb " > #define FOO_BPF_XDP_ADJUST_HEAD_HELPER_COMPAT_LIST "" \ > "xdp " > #define FOO_BPF_PROBE_READ_STR_HELPER_COMPAT_LIST "" \ > "kprobe " \ > "tracepoint " \ > "perf_event " \ > "raw_tracepoint " > ...
Rest looks good to me, just a comment here. How would programs use the compat list? Wouldn't it be nicer to provide a PROG(HELPER) availability query along the lines of ... #if FOO_HAVE_SOCKET_FILTER(skb_load_bytes) == 1 // ... #endif ... where the helper provides these macro functions and results in the header file? So they can be used easily in the code from BPF prog or normal C applications? > v2: > - #define-based output added as a distinct patch. > - "HAVE_" prefix appended to all macro names. > - Output limited to bpf() syscall availability, BPF prog and map types, > helper functions. In this version kernel config options, procfs > parameter or kernel version are intentionally left aside. > - Following the change on helper probes, format for helper probes in > this output style has changed (now a list of compatible program > types). > > Signed-off-by: Quentin Monnet <quentin.mon...@netronome.com>
