[dpdk-dev] [PATCH v7 10/19] vhost: add config flag for postcopy feature

[Maxime Coquelin <maxime.coquelin@redhat.com>]

Postcopy live-migration features relies on userfaultfd,
which was only introduced in kernel v4.3.

This patch introduces a new define to allow building vhost
library on kernels not supporting userfaultfd.

With legacy build system, user has to explicitly set
CONFIG_RTE_LIBRTE_VHOST_POSTCOPY to 'y'.

With Meson build system, RTE_LIBRTE_VHOST_POSTCOPY gets
automatically defined if userfaultfd kernel header is
present.

Suggested-by: Ilya Maximets <i.maximets@samsung.com>
Signed-off-by: Maxime Coquelin <maxime.coquelin@redhat.com>
Acked-by: Ilya Maximets <i.maximets@samsung.com>
---
 config/common_linuxapp       | 1 +
 lib/librte_vhost/meson.build | 2 ++
 2 files changed, 3 insertions(+)

diff --git a/config/common_linuxapp b/config/common_linuxapp
index 485e1467d..424100a75 100644
--- a/config/common_linuxapp
+++ b/config/common_linuxapp
@@ -14,6 +14,7 @@ CONFIG_RTE_LIBRTE_KNI=y
 CONFIG_RTE_LIBRTE_PMD_KNI=y
 CONFIG_RTE_LIBRTE_VHOST=y
 CONFIG_RTE_LIBRTE_VHOST_NUMA=y
+CONFIG_RTE_LIBRTE_VHOST_POSTCOPY=n
 CONFIG_RTE_LIBRTE_PMD_VHOST=y
 CONFIG_RTE_LIBRTE_IFC_PMD=y
 CONFIG_RTE_LIBRTE_PMD_AF_PACKET=y
diff --git a/lib/librte_vhost/meson.build b/lib/librte_vhost/meson.build
index 9d25b4d88..e33e6fc16 100644
--- a/lib/librte_vhost/meson.build
+++ b/lib/librte_vhost/meson.build
@@ -7,6 +7,8 @@ endif
 if has_libnuma == 1
 	dpdk_conf.set10('RTE_LIBRTE_VHOST_NUMA', true)
 endif
+dpdk_conf.set('RTE_LIBRTE_VHOST_POSTCOPY',
+	      cc.has_header('linux/userfaultfd.h'))
 version = 4
 allow_experimental_apis = true
 cflags += '-fno-strict-aliasing'
-- 
2.17.1