On Fri, Dec 10, 2021 at 12:23:59PM +0300, Dmitry Kozlyuk wrote:

2021-12-09 16:39 (UTC+0000), Bruce Richardson:

quoted

On Thu, Dec 09, 2021 at 04:17:08PM +0000, Bruce Richardson wrote:
[...]

quoted

I'm wondering if a reasonable compromise solution might be to have the
build system expose a usable RTE_EXEC_ENV symbol that can be used in C-code
if statements rather than just in ifdefs. That would allow us to easily add
e.g.

if (RTE_EXEC_ENV == rte_env_linux)
    return TEST_SKIPPED;

into each test function needing it. Two lines of C-code is a lot easier to
add and manage than #ifdefs covering the whole file, or alternative lists
in meson.
  

Quick patch to allow C-code comparisons:

diff --git a/lib/eal/meson.build b/lib/eal/meson.build
index 1722924f67..b5b9fa14b4 100644
--- a/lib/eal/meson.build
+++ b/lib/eal/meson.build

@@ -10,6 +10,12 @@ if not is_windows
     subdir('unix')
 endif
 
+exec_envs = {'freebsd': 0, 'linux': 1, 'windows': 2}
+foreach env, id:exec_envs
+    dpdk_conf.set('RTE_ENV_' + env.to_upper(), id)
+endforeach
+dpdk_conf.set('RTE_EXEC_ENV', exec_envs[exec_env])
+
 dpdk_conf.set('RTE_EXEC_ENV_' + exec_env.to_upper(), 1)
 subdir(exec_env)

A slightly simpler patch would just expose the environment as a string as
e.g. "linux", but I think numeric ids just make the code better rather than
having string comparisons. Alternatively, this could also be done via
C-code with ifdefs in EAL, but as it stands this meson change allows:

  if (RTE_EXEC_ENV == RTE_ENV_WINDOWS)
     ...

or:

  switch (RTE_EXEC_ENV) {
    case RTE_ENV_LINUX: ... ; break;
    case RTE_ENV_FREEBSD: ... ; break;
    case RTE_ENV_WINDOWS: ... ; break;
  }

Thoughts?

I like this.
Even outside of tests more code can be made to compile on all platforms
(e.g. ixgbe_wait_for_link_up).
Alternative naming: RTE_EXEC_ENV_IS_* (similar to RTE_CC_IS_*),
which does not allow switch statements, but shortens most practical cases.

Sure. I wonder if it is worthwhile implementing both, since it's not a
large amount of code.

Will Coverity understand that if a condition is always false,
variables beneath still may be used on another platform?

That I don't know, unfortunately. Perhaps some coverity experts can weigh
in.

/Bruce