[v2,1/3] kni: flag deprecated status at build time

  To ensure all users are aware of KNI's deprecated status at build time
we can take the following actions:

1. disable the library by default. It can be re-enabled by setting
   disabled_libs to the empty string (or other string not including
   'kni')

2. add support for a list of deprecated libs to the lib/meson.build file
   so the error message for KNI being disabled includes the fact that it
   is a deprecated library.

3. for the dependent NIC driver, drivers/net/kni, modify its disabled
   message to also reference the fact that KNI is disabled.

NOTE: This is part of the deprecation process for KNI agreed by the DPDK
technical board.[1]

[1] http://mails.dpdk.org/archives/dev/2022-June/243596.html

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
V2: correct dpdk_conf lookup key to RTE_LIB_KNI
---
 doc/guides/prog_guide/kernel_nic_interface.rst | 4 ++++
 drivers/net/kni/meson.build                    | 5 +++++
 lib/meson.build                                | 7 +++++++
 meson_options.txt                              | 2 +-
 4 files changed, 17 insertions(+), 1 deletion(-)

--
2.34.1
  

On Fri, Oct 7, 2022 at 5:01 PM Bruce Richardson
<bruce.richardson@intel.com> wrote:
>
> To ensure all users are aware of KNI's deprecated status at build time
> we can take the following actions:
>
> 1. disable the library by default. It can be re-enabled by setting
>    disabled_libs to the empty string (or other string not including
>    'kni')
>
> 2. add support for a list of deprecated libs to the lib/meson.build file
>    so the error message for KNI being disabled includes the fact that it
>    is a deprecated library.
>
> 3. for the dependent NIC driver, drivers/net/kni, modify its disabled
>    message to also reference the fact that KNI is disabled.
>
> NOTE: This is part of the deprecation process for KNI agreed by the DPDK
> technical board.[1]
>
> [1] http://mails.dpdk.org/archives/dev/2022-June/243596.html
>
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>

I suppose you wanted to go as simple as possible but let me suggest something.
If you think it is not worth, I am ok with the current patch and you can add:
Reviewed-by: David Marchand <david.marchand@redhat.com>


The suggestion:

By exposing the deprecated lib list to meson.build, we can make the
deprecation warning as part of {drivers,lib}/meson.build.
Then the other components depending on a deprecated library don't need
to be updated.
Like:

diff --git a/drivers/meson.build b/drivers/meson.build
index f6ba5ba4fb..f7ef22c9e6 100644
--- a/drivers/meson.build
+++ b/drivers/meson.build
@@ -133,6 +133,9 @@ foreach subpath:subdirs
                 if not is_variable('shared_rte_' + d)
                     build = false
                     reason = 'missing internal dependency, "@0@"'.format(d)
+                    if dpdk_libs_deprecated.contains(d)
+                        reason += ' (deprecated lib)'
+                    endif
                     message('Disabling @1@ [@2@]: missing internal
dependency "@0@"'
                             .format(d, name, 'drivers/' + drv_path))
                 else
diff --git a/drivers/net/kni/meson.build b/drivers/net/kni/meson.build
index 6289aa6cc3..2acc989694 100644
--- a/drivers/net/kni/meson.build
+++ b/drivers/net/kni/meson.build
@@ -6,11 +6,6 @@ if is_windows
     reason = 'not supported on Windows'
     subdir_done()
 endif
-if not dpdk_conf.has('RTE_LIB_KNI')
-    build = false
-    reason = 'needs deprecated lib, "kni"'
-    subdir_done()
-endif

 deps += 'kni'
 sources = files('rte_eth_kni.c')
diff --git a/lib/meson.build b/lib/meson.build
index 264a1671df..a17a5a986a 100644
--- a/lib/meson.build
+++ b/lib/meson.build
@@ -85,7 +85,8 @@ optional_libs = [
         'vhost',
 ]

-deprecated_libs = ['kni']
+dpdk_libs_deprecated += ['kni']
+
 disabled_libs = []
 opt_disabled_libs = run_command(list_dir_globs, get_option('disable_libs'),
         check: true).stdout().split()
@@ -134,11 +135,11 @@ foreach l:libraries
     if disabled_libs.contains(l)
         build = false
         reason = 'explicitly disabled via build config'
-        if deprecated_libs.contains(l)
+        if dpdk_libs_deprecated.contains(l)
             reason += ' (deprecated lib)'
         endif
     else
-        if deprecated_libs.contains(l)
+        if dpdk_libs_deprecated.contains(l)
             warning('Enabling deprecated library, "@0@"'.format(l))
         endif
         subdir(l)
@@ -156,6 +157,9 @@ foreach l:libraries
         if not is_variable('shared_rte_' + d)
             build = false
             reason = 'missing internal dependency, "@0@"'.format(d)
+            if dpdk_libs_deprecated.contains(d)
+                reason += ' (deprecated lib)'
+            endif
             message('Disabling @1@ [@2@]: missing internal dependency "@0@"'
                     .format(d, name, 'lib/' + l))
         else
diff --git a/meson.build b/meson.build
index 8b1b09ead5..8a2d64efef 100644
--- a/meson.build
+++ b/meson.build
@@ -42,6 +42,7 @@ dpdk_chkinc_headers = []
 dpdk_driver_classes = []
 dpdk_drivers = []
 dpdk_extra_ldflags = []
+dpdk_libs_deprecated = []
 dpdk_libs_disabled = []
 dpdk_drvs_disabled = []
 testpmd_drivers_sources = []