On Thu, Sep 17, 2020 at 10:38:12AM +0200, Jiri Olsa wrote: > On Thu, Sep 17, 2020 at 10:04:55AM +0200, Jiri Olsa wrote: > > On Wed, Sep 16, 2020 at 02:47:33PM -0500, Seth Forshee wrote: > > > The requirement to build resolve_btfids whenever CONFIG_DEBUG_INFO_BTF > > > is enabled breaks some cross builds. For example, when building a 64-bit > > > powerpc kernel on amd64 I get: > > > > > > Auto-detecting system features: > > > ... libelf: [ [32mon[m ] > > > ... zlib: [ [32mon[m ] > > > ... bpf: [ [31mOFF[m ] > > > > > > BPF API too old > > > make[6]: *** [Makefile:295: bpfdep] Error 1 > > > > > > The contents of tools/bpf/resolve_btfids/feature/test-bpf.make.output: > > > > > > In file included from /home/sforshee/src/u-k/unstable/tools/arch/powerpc/include/uapi/asm/bitsperlong.h:11, > > > from /usr/include/asm-generic/int-ll64.h:12, > > > from /usr/include/asm-generic/types.h:7, > > > from /usr/include/x86_64-linux-gnu/asm/types.h:1, > > > from /home/sforshee/src/u-k/unstable/tools/include/linux/types.h:10, > > > from /home/sforshee/src/u-k/unstable/tools/include/uapi/linux/bpf.h:11, > > > from test-bpf.c:3: > > > /home/sforshee/src/u-k/unstable/tools/include/asm-generic/bitsperlong.h:14:2: error: #error Inconsistent word size. Check asm/bitsperlong.h > > > 14 | #error Inconsistent word size. Check asm/bitsperlong.h > > > | ^~~~~ > > > > > > This is because tools/arch/powerpc/include/uapi/asm/bitsperlong.h sets > > > __BITS_PER_LONG based on the predefinied compiler macro __powerpc64__, > > > which is not defined by the host compiler. What can we do to get cross > > > builds working again? > > > > could you please share the command line and setup? > > I just reproduced.. checking on fix I still need to check on few things, but patch below should help we might have a problem for cross builds with different endianity than the host because libbpf does not support reading BTF data with different endianity, and we get: BTFIDS vmlinux libbpf: non-native ELF endianness is not supported jirka --- diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile index a88cd4426398..d3c818b8d8d3 100644 --- a/tools/bpf/resolve_btfids/Makefile +++ b/tools/bpf/resolve_btfids/Makefile @@ -1,5 +1,6 @@ # SPDX-License-Identifier: GPL-2.0-only include ../../scripts/Makefile.include +include ../../scripts/Makefile.arch ifeq ($(srctree),) srctree := $(patsubst %/,%,$(dir $(CURDIR))) @@ -29,6 +30,7 @@ endif AR = $(HOSTAR) CC = $(HOSTCC) LD = $(HOSTLD) +ARCH = $(HOSTARCH) OUTPUT ?= $(srctree)/tools/bpf/resolve_btfids/
