2015-07-10 10:29, Stephen Hemminger: > On Fri, 10 Jul 2015 01:43:17 +0200 > Thomas Monjalon <thomas.monjalon at 6wind.com> wrote: > > > 2015-07-09 16:26, Stephen Hemminger: > > > From: Stephen Hemminger <shemming at brocade.com> > > > > > > The build of DPDK may be done on a system where Linux headers > > > in /usr/include (and therefore kernel version macro) are much > > > older than the target runtime system. > > > > It seems strange wanting to build a feature not present in the kernel > > headers. Why not upgrading the build system kernel? > > The build machine is running Debian with stock headers and kernel. > I can see many people having build environments controlled by other > parts of organization where you are not allowed to update packages. > > > > In order to work around this, one solution is to put in simplified > > > kernel header (this is what the compat stuff is already doing). > > > > The other solution (as already suggested by Anatoly) is to have a configure > > script (not an autotool one). It would make clear that VFIO support is not > > built. > > Ref: http://dpdk.org/ml/archives/dev/2015-April/016772.html > > That won't solve the issue.
That allows to see the error earlier and more clearly. > The other possiblities are: > 1. Fail the build if VFIO is configured but headers files are missing. > This is better than surprising user at runtime. > 2. Don't use /usr/include/linux as path as expected path of kernel headers > instead use build path (this is what modules do). The latter one seems to be the right one. There is a name for that technique: cross-compilation. If you want to build DPDK to run on another system with different kernel and libraries, you should adapt the toolchain and libraries headers. And guess what? include/linux/ is part of this toolchain. Problem solved.
