On 4/3/2019 3:22 PM, Ye Xiaolong wrote: > On 04/03, Ferruh Yigit wrote: > [snip] >> >> It seems, 'tools/include/asm/barrier.h' is required for 'smp_wmb()' & >> 'smp_rmb()' in 'xsk.h'. >> We have equivalents of these in DPDK [1], and perhaps it can be possible to >> use >> them and not include this header at all. >> >> in 'rte_eth_af_xdp.c', before including 'xsk.h', we can include an local >> compatibility header which does following should work: >> #define smp_rmb() rte_rmb() >> #define smp_wmb() rte_wmb() >> >> @Xiaolong, what do you think? > > It sounds perfect to me, I'll take it in my next version. > Something to confirm, So we can now assume af_xdp pmd user would use kernel > (say v5.1-rc4) > that contains fixes regarding to xsk.h and libelf, I still need to do > following > changes. > > 1. I shall use <bpf/xsk.h> as xsk.h should be installed in system folders. > 2. `-lelf` is not needed in rte.app.mk > 3. I need to document the libbpf build and install steps in af_xdp.rst > 4. add the above two defines before including xsk.h
Looks good to me, only for item 4) instead of putting those defines into .c file directly, can create a private header in driver folder, put those lines and I assume will need a few includes for rte_rmb as well, and include that header before xsk.h. > > Thanks, > Xiaolong > > >> >> [1] >> https://git.dpdk.org/dpdk/tree/lib/librte_eal/common/include/arch/x86/rte_atomic.h?h=v19.02#n30 >> >>> >>> The one in tools/include also is GPL-2.0 only so it cannot be included >>> from the PMD, which is BSD-3-clause only (and it recursively includes >>> the other arch-specific kernel headers) >>> >>>> Anyway, as Xiaolong mentioned, following is working, can it work from >>>> a distro >>>> point of view: >>>> - get kernel source code (>= v5.1-rc1) >>>> - build libbfp and install >>>> - set 'RTE_KERNELDIR' to point kernel source path >>>> - build dpdk with af_xdp enabled >>> >>> As long as the full kernel tree is required, we cannot enable it in >>> Debian and Ubuntu - we can't have it at build time on the build >>> workers, and also there's the licensing problem. >> >> Got it. >> >> In above steps, 'libbpf' also build from kernel source tree, will it be >> problem >> in you builds to not have it build from source? >> >> If not, taking into account that xsk.h also will be fixed, only >> 'tools/include/asm/barrier.h' remains the problem, and it looks like it can >> be >> solved, please check above. >> >> >>> >>>>> Also, the license in asm/barrier.h is GPL-2.0 only. It is not a >>>>> userspace header so it is not covered by the userspace exception, >>>>> which >>>>> means at the very least the af_xdp PMD shared object is also >>>>> licensed >>>>> under GPL-2.0 only, isn't it? >>>>> >>>> >>>> >>
