> -----Original Message----- > From: Honnappa Nagarahalli <honnappa.nagaraha...@arm.com> > Sent: Tuesday, March 9, 2021 5:05 PM > To: Juraj Linkeš <juraj.lin...@pantheon.tech>; Jerin Jacob > <jerinjac...@gmail.com> > Cc: Bruce Richardson <bruce.richard...@intel.com>; Ruifeng Wang > <ruifeng.w...@arm.com>; vcchu...@amazon.com; Dharmik Thakkar > <dharmik.thak...@arm.com>; hemant.agra...@nxp.com; Ajit Khaparde > (ajit.khapa...@broadcom.com) <ajit.khapa...@broadcom.com>; > ferruh.yi...@intel.com; abo...@pensando.io; lir...@marvell.com; > dev@dpdk.org; nd <n...@arm.com>; nd <n...@arm.com> > Subject: RE: [PATCH v16 1/3] build: disable/enable drivers in Arm builds > > <snip> > > > > > > > > > > > > > On Tue, Mar 09, 2021 at 08:58:39AM +0000, Juraj Linkeš wrote: > > > > > > > Honnappa, Thomas, Bruce, Jerin, you've comments in the past. > > > > > > > Do you have > > > > > > any further input? > > > > > > > > > > > > > > I think we just need to agree on the allowlist/blocklist > > > > > > > mechanism. The current > > > > > > commit allows specifying either an allowlist or a blocklist, > > > > > > but not > > both. > > > > > > However, it would possible to implement specifying both - > > > > > > first we'll allow what's in allowlist and then we'll remove > > > > > > from that set what's > > > > in blocklist. > > > > > > Thoughts? > > > > > > > > > > > > > > > > > > > If we have both, I think limiting to only one is by far the sanest > > > > > > option. > > > +1 > > > > > > > > > I'm not fully convinced by the need to have both, since the > > > > > > blocklist allows wildcarding and exception cases. For example > > > > > > "net/[!i]*" will blocklist all net drivers except those > > > > > > starting with an "i". Admittedly, for usability purposes > > > > > > having an allowlist might > > > > work better. > > > > > > > > > > > > > > > > If we only want to build a handful of drivers then the list > > > > > could be very long > > > > (which was the original reason behind having an allowlist), such as > > > > here: > > > > > https://gerrit.fd.io/r/gitweb?p=vpp.git;a=blob;f=build/external/ > > > > > pa > > > > > ck ag > > > > > es/dpdk.mk;h=c35ac84c27b19411a0cfdf9a3524fdf36024762c;hb=HEAD > > > > > > > > > > An allowlist could also help with maintenance - users won't need > > > > > to add > > > > new drivers to their blocklists (if that's what users need, like > > > > in the case of VPP). > > > > > > > > +1 for allowlist. > > > May be I am missing something here. By creating an allowlist, does > > > it mean drivers are disabled (from compilation) by default? For a > > > server platform, where almost all the drivers can be compiled, does > > > the allowlist > > contain all the drivers? > > > > > > > If no allowlist is specified, then everythin will be built - nothing > > will be filtered. > That's confusing. > If a platform like bluefield has an allow list, a new PMD that gets added > will not > be compiled for that platform unless someone explicitly adds it to the allow > list. > Is my understanding correct?
Yes. > Whereas if the bluefield platform had a block list, then the new PMD would be > compiled for bluefield platform. > Again, yes. Supporting both would give us the option to choose between the two behaviors. > > > > > If we assume by default everything should compile on Arm platform, > > > but allow for few exceptions (where things are really painful to > > > fix, for > > > ex: compiler needs to be fixed), having a blocklist should be > > > shorter/better? > > > > > > > The blocklist is, I think, agreed upon by everyone. The question is > > whether we want to support the allowlist alongside it and there seem > > to be enough reasons to do that. > Sorry, may be this is answered already, but, what additional benefit does > allowlist provide over the blocklist? > VPP could use it: https://gerrit.fd.io/r/gitweb?p=vpp.git;a=blob;f=build/external/packages/dpdk.mk;h=c35ac84c27b19411a0cfdf9a3524fdf36024762c;hb=HEAD They're disabling almost everything so an allowlist would fit there. And they won't need to update the list when a new driver is added (which they won't need). I think it was Jerin who suggested the allowlist. I don't know of an Arm usecase for it, but maybe he has an example. > > > > > By having an allowlist, we will end up with a large part of the code > > > that might not compile on Arm platforms. > > > > > > > > > > > > > > > > > > One final thought, if we add a driver allowlist for cross > > > > > > files, should we also add one as a top-level meson option also > > > > > > for > > consistency? > > > > > > > > > > > > > > > > This definitely makese sense. I was thinking about this and > > > > > wasn't sure > > > > whether I should put it into this commit or a separate one. The > > > > commit evolved a bit and now that it's just an implementation of > > > > an allow/blocklist it makes sense to include a meson option in it > > > > I think > > > > - I'll put it into the next version. > > > > > > > > > > > /Bruce > > > > >
