Re: [dpdk-dev] [RFC PATCH v1] build: kni gcc cross-compilation support

["Juraj Linkeš" <juraj.linkes@pantheon.tech>]

> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Friday, January 29, 2021 4:40 PM
> To: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Cc: thomas@monjalon.net; Ruifeng.Wang@arm.com; jerinjacobk@gmail.com;
> hemant.agrawal@nxp.com; ferruh.yigit@intel.com; aboyer@pensando.io;
> dev@dpdk.org
> Subject: Re: [RFC PATCH v1] build: kni gcc cross-compilation support
> 
> On Fri, Jan 29, 2021 at 03:17:02PM +0000, Juraj Linkeš wrote:
> >
> >
> > > -----Original Message-----
> > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > Sent: Friday, January 29, 2021 4:01 PM
> > > To: Juraj Linkeš <juraj.linkes@pantheon.tech>
> > > Cc: thomas@monjalon.net; Ruifeng.Wang@arm.com;
> > > jerinjacobk@gmail.com; hemant.agrawal@nxp.com;
> > > ferruh.yigit@intel.com; aboyer@pensando.io; dev@dpdk.org
> > > Subject: Re: [RFC PATCH v1] build: kni gcc cross-compilation support
> > >
> > > On Fri, Jan 29, 2021 at 02:47:57PM +0000, Juraj Linkeš wrote:
> > > >
> > > >
> > > > > -----Original Message-----
> > > > > From: Bruce Richardson <bruce.richardson@intel.com>
> > > > > Sent: Friday, January 29, 2021 3:42 PM
> > > > > To: Juraj Linkeš <juraj.linkes@pantheon.tech>
> > > > > Cc: thomas@monjalon.net; Ruifeng.Wang@arm.com;
> > > > > jerinjacobk@gmail.com; hemant.agrawal@nxp.com;
> > > > > ferruh.yigit@intel.com; aboyer@pensando.io; dev@dpdk.org
> > > > > Subject: Re: [RFC PATCH v1] build: kni gcc cross-compilation
> > > > > support
> > > > >
> > > <snip>
> > > > > > > Can we find some way of getting it working for both cases.
> > > > > > > For native builds we want:
> > > > > > >
> > > > > > > * build kernel-dir = /lib/modules/<ver>/build
> > > > > > > * install dir = /lib/modules/<ver>/extra/dpdk
> > > > > > >
> > > > > > > What are the expected equivalent paths for cross building?
> > > > > > >
> > > > > >
> > > > > > The ubuntu1804 packages are installing aarch64 cross files to
> > > > > > /usr/aarch64-
> > > > > linux-gnu, so we could install it to /usr/aarch64-linux-
> > > > > gnu/lib/modules/<ver>/extra/dpdk, or
> > > > > /usr/<cross_triple>/lib/modules/<ver>/extra/dpdk in general. I
> > > > > think we can get <ver> from 'make kernelversion', so that would
> > > > > work, although I'm not sure this is the right place.
> > > > > >
> > > > > So what do you specify as the "kernel_dir" for the cross compile?
> > > > >
> > > >
> > > > The place where I cloned (and cross-compiled) linux sources: $HOME/linux.
> > > >
> > > So I think the key problem is that for cross-compilation you need
> > > two completely independent paths, while for native builds the two can be
> linked. Is that correct?
> >
> > Assuming that we want to install cross modules, then yes, although
> > it's incomplete. There's also the scenario when a user would use
> > different kernel_dir than the default for native builds. I don't know
> > why anyone would do that, but it is a theoretical possibility :-)
> 
> In the cross-compile install case, is the prefix /usr/aarch64-linux-gnu/ coming
> from a DESTDIR environment variable? If it is, then we could just use the
> kernel_dir option for the build path, and always install to /lib/modules/<ver>/...
> allowing any cross-compiler relocation to take care of the rest.

It's not coming from anywhere. What I meant is that an ubuntu package such as 'libatomic1-arm64-cross' installs its headers/libs under /usr/aarch64-linux-gnu/.