Re: [dpdk-stable] [EXT] Re: [dpdk-dev] [PATCH v2 01/13] security: fix verification of parameters

[Bruce Richardson <bruce.richardson@intel.com>]

On Wed, Apr 08, 2020 at 07:51:35PM +0200, Thomas Monjalon wrote:
> 08/04/2020 17:49, Lukasz Wojciechowski:
> > Hi guys,
> > 
> > I don't know what is the current status of "legacy" build using 
> > gnumakes, so I added the new DEBUG flag to config just as it was done in 
> > other libs like eventdev.
> > Many guides still point config files as the one that should be changed 
> > in order to enable some features, so I thought I should add it there.
> > 
> > If I understand well the official build system now is the one based on 
> > using meson and ninja, however it hasn't got anything similar to the 
> > gnamakefiles system, e.g.
> > in the meson.build file for libraries all the libraries have build 
> > variable set to true and there are few ifs that check it, but as it's 
> > set to true all libraries build always.
> > And each library considered there defines RTE_LIBRTE_[LIBRARY_NAME]. 
> > It's kind of weird.
> > 
> >     foreach l:libraries
> >     *    build = true**
> >     *    reason = '<unknown reason>' # set if build == false to explain why
> >          ...
> >     *    if not build*
> >              dpdk_libs_disabled += name
> >              set_variable(name.underscorify() + '_disable_reason', reason)
> >          else
> >              enabled_libs += name
> >     *dpdk_conf.set('RTE_LIBRTE_' + name.to_upper(), 1)*
> >          ...
> > 
> > Have you think about reusing config files in meson configuration and 
> > have a single point of configuration? Of course all meson flags can 
> > overwrite the default config.
> 
> This is on purpose.
> We are removing most of compile-time options with meson.
> 
> I think we can use a global option for debug-specific code.
> Bruce, what do you recommend?
> 
Meson has a built-in global debug setting which could be used. However,
that may be too course-grained. If that is the case there are a couple of
options:

1 Each library can have it's own debug flag defined, which is set on
  the commandline in CFLAGS. Can be done right now - just reuse any of the
  debug variables in the existing make config files (stripping off the
  CONFIG_), e.g. CFLAGS=-DRTE_MALLOC_DEBUG
2 Since that is perhaps not the most usable - though easiest to implement -
  we can look to add a general debug option (or couple of options) in
  meson, e.g. debug_libs=, debug_drivers=, where each option takes a list of
  libs or drivers to pass the debug flags to. This will require a little
  work in the meson build infrastructure, but is not that hard. The harder
  part is standardizing the debug flags across all components.

The advantage of #1 is that it works today and just needs some
documentation for each lib/driver what it's debug flags are. The advantage
of #2 is more usability, but it requires a lot more work to standardize
IMHO.

/Bruce