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

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

On Thu, Apr 09, 2020 at 12:54:10PM +0200, Thomas Monjalon wrote:
> 09/04/2020 12:14, Bruce Richardson:
> > 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.
> 
> In this case, we need a general option as the one already provided by meson.
> It means: "I am not in production, I want to see anything behaving wrong
> in the datapath."
> "Anything" means we don't need a per-library switch.
> And for the other needs (out of fast path), we have a new function:
> 	rte_log_can_log(mylogtype, RTE_LOG_DEBUG)
> 
To use the general option in meson something like below is probably all
that is needed to flag the debug build to all components:

diff --git a/config/meson.build b/config/meson.build
index 49482091d..b01cd1251 100644
--- a/config/meson.build
+++ b/config/meson.build
@@ -176,6 +176,10 @@ endif
 # add -include rte_config to cflags
 add_project_arguments('-include', 'rte_config.h', language: 'c')

+if get_option('debug')
+       add_project_arguments('-DDEBUG', language: 'c')
+endif
+
 # enable extra warnings and disable any unwanted warnings
 warning_flags = [
        # -Wall is added by meson by default, so add -Wextra only