On 6/13/2016 11:21 AM, Thomas Monjalon wrote: > 2016-06-13 11:04, Ferruh Yigit: >> On 6/13/2016 10:29 AM, Thomas Monjalon wrote: >>> 2016-06-10 19:32, Ferruh Yigit: >>>> As stated in the comment: >>>> Order is important: from higher level to lower level >>>> >>>> This is an attempt to make the layering order better respected. >>>> >>>> Limit scope of --whole-archive to pmd libraries >>> >>> Compared to the link order in the v2, you did two things: >>> 1/ move PMDs to the first position >>> 2/ restrict --whole-archive to PMDs only >>> >>> Having the PMDs first, helps the linker to get all the PMD dependencies >>> in the static binary. Thus it seems we do not need --whole-archive >>> for the PMD dependencies (ethdev, mbuf, etc). >>> But, if an external PMD is loaded via dlopen, it is possible that it >>> needs a symbol which was not used by the internal PMDs. So it will not >>> be found in the statically linked binary. >>> Let's take another example: if we disable the internal PMDs with their >>> config options from the static build, and we decide to build them >>> separately as DSOs. We won't be able to load them as plugins because >>> they depend on symbols which won't be found in the static binary. >> >> So you want to keep all objects in final binary (used or unused) because >> of the possibility that any plugin may use them. > > Yes > >> But what is the list to include here, whole dpdk?, -since we may not >> know what API will plugin call. > > The list of the libraries candidates to be called from a driver can be > discussed. The top layers like lpm or distributor should not be in this > list I think. > >> What I am confused is --whole-archive only used when dpdk compiled as >> static, if dpdk compiled as shared, each PMD should have proper >> dependencies [1], and if external PMD compiled properly there shouldn't >> be a problem. So do we have a case that dpdk compiled statically into >> final binary but we still want to load some plugins dynamically? > > Yes a plugin can be loaded from a static binary. > Breaking this feature would need a separate discussion and notices. Thanks for clarifying, I wasn't aware of this. So I am leaving this patch, please just ping if anything required from me.
> >>> To make it short, the PMDs must be considered as plugins. Therefore, we >>> must not rely on their availability to link the required symbols in >>> a static binary. >>> To make sure the plugin loading will be always well achieved, we must >>> link the static PMDs at the last position. >> >> I think this is not the issue of linking PMD's first or last, but >> expanding --whole-archive to cover other libraries other than PMDs. > > Yes, linking PMD at the end is a way to force us to keep some libraries > in --whole-archive. > >>> If you agree, I vote for the v2 of this patchset. >> >> If this is breaking something and best way to fix is not in external PMD >> but in here, please feel free to go with v2. > > I don't see any other solution. > But I'm sure we could discuss it more and/or improve it in the future. >
