From 849308d20716f40452e70a230f3a403ee88b207d Mon Sep 17 00:00:00 2001
From: Stefano Brivio <sbrivio@redhat.com>
Date: Thu, 21 Oct 2021 01:19:27 +0200
Subject: Makefile, tcp: Don't try to use tcpi_snd_wnd from tcp_info on pre-5.3
 kernels

Detect missing tcpi_snd_wnd in struct tcp_info at build time,
otherwise build fails with a pre-5.3 linux/tcp.h header.

Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
---
 Makefile | 5 +++++
 1 file changed, 5 insertions(+)

(limited to 'Makefile')

diff --git a/Makefile b/Makefile
index 85d7400..83140ad 100644
--- a/Makefile
+++ b/Makefile
@@ -29,6 +29,11 @@ endif
 endif
 endif
 
+C := \#include <linux/tcp.h>\nstruct tcp_info x = { .tcpi_snd_wnd = 0 };
+ifeq ($(shell printf "$(C)" | $(CC) -S -xc - -o - >/dev/null 2>&1; echo $$?),0)
+	CFLAGS += -DHAS_SND_WND
+endif
+
 prefix ?= /usr/local
 
 all: passt pasta passt4netns qrap
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