Content:
1. Overview
2. Directory structure
3. HOWTO add a new feature patch(es)
4. HOWTO add backport patches
5. Check compilation
6. Submitting to Gerrit


Overview:
---------
The general idea is based on compat-wireless project https://lkml.org/lkml/2011/9/9/327
Compat Wiki:
https://backports.wiki.kernel.org/index.php/Main_Page
https://backports.wiki.kernel.org/index.php/Documentation

Also it utilizes autotools.

Directory structure:
--------------------
MLNX_OFED-3.x (mlnx_rdma) git tree structure:
Compat files:
	compat/
	include/linux/compat*.h
	ofed_scripts/gen-compat-autoconf.sh
	ofed_scripts/gen-compat-config.sh
	include/linux/<headers to update existing headers by #include_next and adding new stuff>*.h

Autotools:
	compat/config
	compat/autogen.sh
	compat/configure.ac

Feautes (Each feautre should be a separate directory):
	features/<index for sorting patch apply order>-<feaure name>

Backport patches:
	backports/<one patch file for each module!>

Kernel subtree based on upstream kernel:
	include/
	drivers/
	net/

---------------------

Compilation procedure:

# cd mlnx_rdma
# git checkout master
# ln -s ofed_scripts/configure
# ln -s ofed_scripts/makefile
# ln -s ofed_scripts/Makefile

# ./configure <params>
E.g.: ./configure --with-core-mod --with-user_mad-mod --with-user_access-mod --with-addr_trans-mod --with-mlx4-mod --with-mlx4_en-mod --with-ipoib-mod --with-srp-mod --with-rds-mod --with-iser-mod

Note: If "backports_applied" file exist then backport patches will not be applied.

# make distclean
# make
# make install

HOWTO add a new feature/fix:
----------------------------
Start with updated branch (equal to “master”).

Add the new code.
Check compilation on the latest kernel base.
# ./configure <params> --without-backport-patches

Note: Provide path to kernel sources if needed: --kernel-version <version> --kernel-sources <path to sources>

# make distclean
# make
# make install

Check your feature.
Commit the changes.
Add backports if required.
See "Check compilation".

Note: Make sure your commits pass linux/scripts/checkpatch.pl
      Backport patches may not pass this check


HOWTO add backport patches:
---------------------------
Start with updated branch (eg: equal to “master”).

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!! NOTE: BACKPORT PATCHES MAY CHANGE FILES UNDER FOLLOWING DIRECTORIES                                               !!!
!!!			include/rdma/                                                                                 !!!
!!!			include/linux/mlx4/                                                                           !!!
!!!			include/linux/mlx5/                                                                           !!!
!!!			drivers/                                                                                      !!!
!!!			net/                                                                                          !!!
!!!			AND SHOULD NOT TOUCH FILES UNDER ofed_scripts, compat and compat headers under include/linux/ !!!
!!! CHANGES TO THE FILES UNDER ofed_scripts, compat and include/linux/compat*.h SHOULD BE COMMITTED DIRECTLY          !!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

$ ln -s ofed_scripts/configure
$ ln -s ofed_scripts/makefile
$ ln -s ofed_scripts/Makefile
$ /bin/rm -f backports_applied

Run configure (check parameters)
$ ./configure --with-core-mod --with-user_mad-mod --with-user_access-mod --with-addr_trans-mod --with-mlx4-mod --with-mlx4_en-mod --with-ipoib-mod --with-srp-mod --with-rds-mod --with-iser-mod

All backports are applied.

$ make KBUILD_NOCMDDEP=1 2>&1 | tee log

In case of undefined variable/function refer to:
https://backports.wiki.kernel.org/index.php/Documentation/compat

If some functionality was backported to some supported Distro need to add CONFIG_COMPAT_... flag (or even better, use autotools
and define flags like HAVE_... see compat/config/rdma.m4):
For example, "netdev_get_prio_tc_map" was added in 2.6.39 but backported to RHEL6.[23]
ifeq ($(RHEL_MAJOR),6)
 CFLAGS += -DCONFIG_COMPAT_IS_PRIO_TC_MAP
 ...
endif

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 0bf5a9d..f0f75b6 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -1844,10 +1844,14 @@ static int cma_resolve_iboe_route(struct rdma_id_private *id_priv)
        route->path_rec->reversible = 1;
        route->path_rec->pkey = cpu_to_be16(0xffff);
        route->path_rec->mtu_selector = IB_SA_EQ;
+#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,39)) || defined(CONFIG_COMPAT_IS_PRIO_TC_MAP)
        route->path_rec->sl = netdev_get_prio_tc_map(
                        ndev->priv_flags & IFF_802_1Q_VLAN ?
                                vlan_dev_real_dev(ndev) : ndev,
                        rt_tos2priority(id_priv->tos));
+#else
+       route->path_rec->sl = id_priv->tos >> 5;
+#endif

Create a new backport patch from the diff above:
1. Commit the change.
2. Squash/Fixup the commit to the original commit that backported the relevant module (unless
you are backporting a new module).
3. Get updated/new patches:
$ ./ofed_scripts/ofed_get_patches.sh
Change branch to the original (E.g. “master”)
Update/add new relevant patches under "backports" directory
$ cp -a ./backports_new/0XXX-<new patch>.patch backports
$ git add backports
$ git commit -s -m ”BACKPORTS: Added RHEL6.[23] support” backports/


Check compilation:
------------------
Use your user and not "root".
$ cd /mswg/projects/art
$ git_url=<git url> git_branch=<git branch> ./build mlnx_rdma


Submitting to Gerrit:
---------------------
Please refer to
http://wiki.lab.mtl.com/tiki/tiki-index.php?page=Code+Review&structure=OFED-LE#Gerrit