Re: 16.07-rc2 issue with rte_rtm_init(void) constructor

[Thomas Monjalon <thomas.monjalon@6wind.com>]

2016-07-14 09:36, Damjan Marion:
> 
> > On 14 Jul 2016, at 10:20, Thomas Monjalon <thomas.monjalon@6wind.com> wrote:
> > 
> > 2016-07-13 22:58, Damjan Marion:
> >> I have issues with linking application to 16.07-rc2.
> >> 
> >> Looks like reason is constructor function in include file,
> >> so our unit test apps are failing to link as they are not linked with dpdk libs.
> >> (and they should not be as they are not calling any dpdk function).
> > 
> > I don't understand:
> > Why are you linking DPDK if you do not use any DPDK function?
> 
> If i simplify it, i have 4 components:
> 
> 1. libdpdk
> 2. libXXX
> 3. app-A
> 4. app-B
> 
> libXXX includes some dpdk headers, mainly because of data structures like rte_mbuf, and some functions are calling
> functions form libdpdk.
> 
> app-A links against libdpdk and libXXX
> app-B links against libXXX only and only uses functions from libXXX which doesn’t have dpdk dependency
> 
> This is working fine in 14.04. In 14.07 rte_rtm_init() implants himself into libXXX as it is defined
> in header file, and that causes linking to fail due to missing rte_cpu_get_flag_enabled().

OK I better understand :)

> >> static inline void __attribute__((constructor))
> >> rte_rtm_init(void)
> >> {
> >>        rtm_supported = rte_cpu_get_flag_enabled(RTE_CPUFLAG_RTM);
> >> }
> >> 
> >> linking fails with:
> >> dpdk/include/rte_spinlock.h:103: undefined reference to `rte_cpu_get_flag_enabled’
> >> 
> >> Is there any chance that this one is moved to some .c file, so it is loaded
> >> only when it is really needed?
> > 
> > Yes it could be moved to lib/librte_eal/common/arch/x86/.
> 
> Any chance to get this in 16.07 ?

Yes maybe if you submit a patch quickly and it is clean enough.