[PATCH v2] build: make buffer headroom configurable

[Parthakumar Roy <partha.roy.tx@gmail.com>]

The default value for RTE_PKTMBUF_HEADROOM used to be set in
config/rte_config.h. This patch removes it from the file and
instead, a meson option, pkt_mbuf_headroom, is introduced to make
headroom tunable from the build process.

Signed-off-by: Parthakumar Roy <Parthakumar.Roy@ibm.com>
---
 config/meson.build  | 1 +
 config/rte_config.h | 1 -
 meson_options.txt   | 2 ++
 3 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/config/meson.build b/config/meson.build
index a9ccd56deb..f90ff0a290 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -346,6 +346,7 @@ dpdk_conf.set('RTE_MAX_ETHPORTS', get_option('max_ethports'))
 dpdk_conf.set('RTE_LIBEAL_USE_HPET', get_option('use_hpet'))
 dpdk_conf.set('RTE_ENABLE_STDATOMIC', get_option('enable_stdatomic'))
 dpdk_conf.set('RTE_ENABLE_TRACE_FP', get_option('enable_trace_fp'))
+dpdk_conf.set('RTE_PKTMBUF_HEADROOM', get_option('pkt_mbuf_headroom'))
 # values which have defaults which may be overridden
 dpdk_conf.set('RTE_MAX_VFIO_GROUPS', 64)
 dpdk_conf.set('RTE_DRIVER_MEMPOOL_BUCKET_SIZE_KB', 64)
diff --git a/config/rte_config.h b/config/rte_config.h
index da265d7dd2..505199f2fe 100644
--- a/config/rte_config.h
+++ b/config/rte_config.h
@@ -51,7 +51,6 @@
 
 /* mbuf defines */
 #define RTE_MBUF_DEFAULT_MEMPOOL_OPS "ring_mp_mc"
-#define RTE_PKTMBUF_HEADROOM 128
 
 /* ether defines */
 #define RTE_MAX_QUEUES_PER_PORT 1024
diff --git a/meson_options.txt b/meson_options.txt
index 50a9d3669d..68f378c401 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -40,6 +40,8 @@ option('machine', type: 'string', value: 'auto', description:
        'Alias of cpu_instruction_set.')
 option('max_ethports', type: 'integer', value: 32, description:
        'maximum number of Ethernet devices')
+option('pkt_mbuf_headroom', type: 'integer', value: 128, description:
+       'number of bytes skipped on Rx at the start of the packet buffer to leave room for additional packet headers')
 option('max_lcores', type: 'string', value: 'default', description:
        'Set maximum number of cores/threads supported by EAL; "default" is different per-arch, "detect" detects the number of cores on the build machine.')
 option('max_numa_nodes', type: 'string', value: 'default', description:
-- 
2.34.1