2015-03-04 13:49, Bruce Richardson: > On Wed, Mar 04, 2015 at 03:41:49PM +0200, Panu Matilainen wrote: > > On 03/04/2015 03:31 PM, Bruce Richardson wrote: > > >On Wed, Mar 04, 2015 at 03:24:12PM +0200, Panu Matilainen wrote: > > >>On 03/04/2015 03:08 PM, Bruce Richardson wrote: > > >>>On Wed, Mar 04, 2015 at 06:28:05AM -0500, Neil Horman wrote: > > >>>>On Wed, Mar 04, 2015 at 01:05:07PM +0200, Panu Matilainen wrote: > > >>>>>On 03/04/2015 11:24 AM, Thomas Monjalon wrote: > > >>>>>>Hi Panu, > > >>>>>> > > >>>>>>2015-03-04 08:17, Panu Matilainen: > > >>>>>>>With symbol versioning its vital that developers test their code in > > >>>>>>>shared library mode, otherwise we'll be playing "add the forgotten > > >>>>>>>symbol export" from here to eternity. > > >>>>>> > > >>>>>>Yes we must improve the sanity checks. > > >>>>>>A lot of options must be tested (or removed) and not only shared libs. > > >>>>>>But the error you reported before (missing export of > > >>>>>>rte_eth_dev_release_port) > > >>>>>>cannot be seen even with this patch. > > >>>>> > > >>>>>I know, I didn't say it would have directly caught it. It would've > > >>>>>likely > > >>>>>been found earlier though, if nothing else then in testing of the new > > >>>>>librte_pmd_null which clearly nobody had tried in shared lib > > >>>>>configuration. > > >>>>> > > >>>>This is accurate. The default config is a tool, in the sense that it > > >>>>leverages > > >>>>the implicit testing of any users who are experimenting with the DPDK. > > >>>>Any > > >>>>users out there using the DPDK test/example applications would have > > >>>>realized > > >>>>something was amiss when the testpmd app refused to run with the null > > >>>>or pcap > > >>>>pmd, since there was a missing symbol. That "social fuzzing" has > > >>>>value, but it > > >>>>only works if the defaults are carefully selected. Currently, building > > >>>>for > > >>>>shared libraries exposes more existing bugs than static libraries, and > > >>>>so we > > >>>>should set that as our default so as to catch them. > > >>>> > > >>>>>>It means we need more tools. > > >>>>>>Though, default configuration is not a tool. > > >>>>> > > >>>>>Yes, default config is not a tool, its a recommendation of sorts both > > >>>>>for > > >>>>>developers and users. It also tends to be the setup that is rarely > > >>>>>broken > > >>>>>because it happens to get the most testing :) > > >>>>> > > >>>>And it is a tool (see above). > > >>>> > > >>>>>> > > >>>>>>>By defaulting to shared we should catch more of these cases early, > > >>>>>>>but without taking away anybodys ability to build static. > > >>>>>> > > >>>>>>Shared libraries are convenient for distributions but have a > > >>>>>>performance > > >>>>>>impact. I think that static build must remain the default choice. > > >>>>> > > >>>> > > >>>>If utmost performance is the concern, isn't it reasonable to assume > > >>>>that users > > >>>>in that demographic will customize their configuration to achieve that? > > >>>> No one > > >>>>assumes that something is tuned to be perfect for their needs out of > > >>>>the box if > > >>>>their needs are extreemely biased to a single quality. The best course > > >>>>of > > >>>>action here is to set the default to be adventageous toward catching > > >>>>bugs, and > > >>>>document the changes needed to bias for performance. > > >>>> > > >>>>>For distros, this is not a matter of *convenience*, its the only > > >>>>>technically > > >>>>>feasible choice. > > >>> > > >>>As I understand it, build for the "default" cpu rather than "native" is > > >>>the only > > >>>feasible choice also, so how about re-introducing a new defconfig file > > >>>for > > >>>"default" (or perhaps better name), where you have lowest-common > > >>>denominator > > >>>instruction-set and building for shared libraries? > > >>>Would that work for everyone, or do people feel it would be too > > >>>confusing to have > > >>>more defconfig files available? > > >> > > >>Given the opposition to defaulting to shared, another config file seems > > >>like > > >>a fair compromise to me, whether "default" or something else. As for the > > >>naming, one possibility would be calling it "shared", implying both > > >>lowest-common denominator instruction set to be shareable across many > > >>systems and shared libraries. > > >> > > >> - Panu - > > > > > >The naming scheme for configs is meant to be: > > >"ARCH-MACHINE-EXECENV-TOOLCHAIN" > > >as documented in the Getting Started Guide. "Default" has been used up > > >till now > > >to refer to the lowest common denominator instruction set supported, which > > >for > > >x86_64 is a core2 baseline, I believe. "shared" doesn't really fit into > > >this > > >naming scheme, and there is nothing to allow extra notes to be added to the > > >name. > > > > Right, but then there's "ivshmem" that doesn't fit that description either > > AFAICS. > > Ah, yes, forgotten about that one! :-)
off-topic: I think we should remove "#ifdef RTE_LIBRTE_IVSHMEM" in EAL and then remove defconfig_x86_64-ivshmem-linuxapp-*. > > >Without changing this scheme, I would suggest we rename "default" to > > >"generic", > > >which I think is a slightly better term for it, and we set the > > >"x86_64-generic-linuxapp-gcc" target to build shared libs. > > > > Works for me. It is indeed more descriptive than either "default" or > > "shared" for the purpose. +1 for x86_64-generic-linuxapp-gcc
