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
