Building Krnlmon with Bazel

Krnlmon has an experimental Bazel buildsystem. It is not integrated with the main CMake build, and is thus of use only to maintainers as a way to do test builds or run unit tests.

Prerequisites

To use the Bazel buildsystem, you will need to install the following packages on your development platform.

Bazel. We have tested with versions 7.1.2 and 7.4.0.
Netlink library (libnl-3)
Target SDE (DPDK or ES2K). Krnlmon does not support Tofino.

The buildsystem downloads private copies of Abseil, Googletest, and SAI.

Environment Variables

The Bazel buildsystem requires that the following environment variables be defined.

SDE_INSTALL: Path to the SDE install directory.

Build Options

The buildsystem supports the following command-line options. They may be specified before or after the target(s).

--config {dpdk|es2k}

TDI target to support. Equivalent to the TDI_TARGET={dpdk|es2k} cmake variable or the --target={dpdk|es2k} helper script option.

--define target={dpdk|es2k}

Alternative to the --config flag.

--//flags:ovs={true|false}

Whether to support OVSP4RT. Equivalent to the WITH_OVSP4RT={true|false} cmake variable or (in the negative) the --no-ovs helper script option.

Specify yes, true, or 1 to enable support, and no, false, or 0 to disable it.

Useful Targets

:krnlmon: Krnlmon library (libkrnlmon.so).
:dummy_krnlmon: Dummy application. Used to check for link errors.

Examples

Build krnlmon for DPDK

We are using the --define option and specifying it after the build target.

bazel build //:krnlmon --define target=dpdk

Build for ES2K without OVS

We are using --config instead of define and specifying the options before the target.

bazel build --config es2k --//flags:ovs=no //:krnlmon

Build dummy application

Check for link issues

The dummy_krnlmon target links the krnlmon library with a dummy main program. This allows you to check for unresolved external symbols in the library.

bazel build --config dpdk //:dummy_krnlmon

Check for RPATH issues

You can check for RPATH problems by issuing the ldd comand and looking for missing libraries in its output.

ldd bazel-bin/dummy_krnlmon

Run unit tests

To build and run the unit tests for ES2K:

bazel test --config es2k //switchlink:all //switchsde:all

Sample output:

INFO: Analyzed 23 targets (2 packages loaded, 92 targets configured).
INFO: Found 18 targets and 5 test targets...
INFO: Elapsed time: 2.372s, Critical Path: 1.79s
INFO: 34 processes: 13 internal, 21 linux-sandbox.
INFO: Build completed successfully, 34 total actions
//switchlink:switchlink_address_test                           PASSED in 0.0s
//switchlink:switchlink_link_test                              PASSED in 0.1s
//switchlink:switchlink_neigh_test                             PASSED in 0.0s
//switchlink:switchlink_route_test                             PASSED in 0.0s
//switchsde:switchsde_test                                     PASSED in 0.1s

Executed 5 out of 5 tests: 5 tests pass.