On Tue, 2016-08-30 at 23:38 +0200, Julian Ospald wrote:
> -dnl Check if we have <linux/bpf.h> for EM_BPF disassembly.
> -AC_CHECK_HEADERS(linux/bpf.h)
> -AM_CONDITIONAL(HAVE_LINUX_BPF_H, [test "x$ac_cv_header_linux_bpf_h" =
> "xyes"])
> +dnl Check if we have <linux/bpf.h> for EM_BPF disassembly and it has the
> required defines
> +AC_COMPILE_IFELSE(
> + [AC_LANG_PROGRAM(
> + [#include <linux/bpf.h>],
> + [int foo=BPF_PSEUDO_MAP_FD; return 0;]
> + )],
> + [have_bpf="true"],
> + [have_bpf="false"]
> +)
> +
> +if test "$have_bpf" = "true" ; then
> + AC_DEFINE([HAVE_LINUX_BPF_H], [1], [if we have <linux/bpf.h> for EM_BPF
> disassembly])
> +fi
> +AM_CONDITIONAL(HAVE_LINUX_BPF_H, [test "$have_bpf" = "true"])
Thanks, that does look like the correct configure check.
But it seems that BPF_PSEUDO_MAP_FD is the only missing constant
introduced since 3.18 (when linux/bpf.h was added) that we use.
So maybe we could simply define it ourselves when not found. So we can
build against any linux/bpf.h out there.
What do people think of the following?
diff --git a/libcpu/bpf_disasm.c b/libcpu/bpf_disasm.c
index 153dba9..e4bbae4 100644
--- a/libcpu/bpf_disasm.c
+++ b/libcpu/bpf_disasm.c
@@ -40,6 +40,10 @@
#include "../libelf/common.h"
#include "../libebl/libeblP.h"
+/* BPF_PSEUDO_MAP_FD was only introduced in linux 3.20. */
+#ifndef BPF_PSEUDO_MAP_FD
+ #define BPF_PSEUDO_MAP_FD 1
+#endif
static const char class_string[8][8] = {
[BPF_LD] = "ld",
Thanks,
Mark
