On Thu, Mar 25, 2021 at 9:13 PM Nishanth Menon via
lists.openembedded.org <nm=ti.com@...> wrote:

When cross-compiling with v5.12-rc3, prepare fails[1] build of vdso at
the objcopy stage since it seems to be using the local host's objcopy
rather than the cross-compile version we want it to use.

This can be trivially reproduced in a localbuild of the kernel
following the build parameters provided in the process[2]

Lets fix this by passing OBJCOPY over to the kernel.

As I mentioned to Denys, I hadn't seen this. Consulting the
maintainers file would have found me as a good addition to the cc'.

I'm doing some other work on make-mod-scripts dependencies right now,
so I've pulled this in and will re-test against all of the active
kernel versions in master.

But I don't think that make-mod-scripts is the only place we'd need
this, if it is indeed happening on the tip of all the supported
versions. There are routes to have the prepare steps run, without a
make-mod-scripts dependency.

We've already made the mistake of letting the make-mod-scrips and
kernel build parameters diverge (see AR=${KERNEL_AR}), so I need to
spend a few minutes getting them back in sync.

I was just able to build and boot qemuarm64 on 5.12-rc4, so there's
something different about your config than my setup. We need to figure
that out. It could be a .config triggering different components to be
built, but unlikely given vdso being involved.

qemuarm64 login: root
root@qemuarm64:~# uname -a
Linux qemuarm64 5.12.0-rc4-yoctodev-standard #1 SMP PREEMPT Mon Mar 22
18:46:22 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
root@qemuarm64:~#

[1] https://pastebin.ubuntu.com/p/pNcQtb93wr/
[2] https://pastebin.ubuntu.com/p/vZGqgh9Sq5/
Signed-off-by: Nishanth Menon <nm@...>
---

NOTE:
1. This is a different problem and is not resolved with
https://lists.openembedded.org/g/openembedded-core/message/149943

2. Though reproduced during a dunfell build, this should probably
apply else where as well.

3. I have'nt been able to cleanly bisect things, but my best guess was
that this might be a consequence of kernel fixup exposing this.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a5b8ca97fbf8300a5e21c393df25ce6f521e7939

meta/classes/kernel-arch.bbclass | 3 +++
meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb | 2 +-
2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/meta/classes/kernel-arch.bbclass b/meta/classes/kernel-arch.bbclass
index 07ec242e63bb..3d25fc7ac531 100644
--- a/meta/classes/kernel-arch.bbclass
+++ b/meta/classes/kernel-arch.bbclass
@@ -60,9 +60,12 @@ TARGET_LD_KERNEL_ARCH ?= ""
HOST_LD_KERNEL_ARCH ?= "${TARGET_LD_KERNEL_ARCH}"
TARGET_AR_KERNEL_ARCH ?= ""
HOST_AR_KERNEL_ARCH ?= "${TARGET_AR_KERNEL_ARCH}"
+TARGET_OBJCOPY_KERNEL_ARCH ?= ""
+HOST_OBJCOPY_KERNEL_ARCH ?= "${TARGET_OBJCOPY_KERNEL_ARCH}"

We shouldn't need this TARGET_OBJCOPY_KERNEL_ARCH ->
HOST_OBJCOPY_KERNEL_ARCH, I can't think of how objcopy would be using
them.

Are you setting them to some value in your builds ?

KERNEL_CC = "${CCACHE}${HOST_PREFIX}gcc ${HOST_CC_KERNEL_ARCH} -fuse-ld=bfd ${DEBUG_PREFIX_MAP} -fdebug-prefix-map=${STAGING_KERNEL_DIR}=${KERNEL_SRC_PATH}"
KERNEL_LD = "${CCACHE}${HOST_PREFIX}ld.bfd ${HOST_LD_KERNEL_ARCH}"
KERNEL_AR = "${CCACHE}${HOST_PREFIX}ar ${HOST_AR_KERNEL_ARCH}"
+KERNEL_OBJCOPY = "${CCACHE}${HOST_PREFIX}objcopy ${HOST_OBJCOPY_KERNEL_ARCH}"

The main kernel Makefile already defines, and the standard env should
already have both CROSS_COMPILE and OBJCOPY defined to be the target
version.

Makefile:OBJCOPY = $(CROSS_COMPILE)objcopy

So we really have to pass this, when fundamentally it is the same
definition as what the defaults give us.

What does that resolve to in your builds ? In mine, when I dump the
objcopy value from within the kernel build, I get:

| /opt/poky/build/tmp/work-shared/qemuarm64/kernel-source/Makefile:443:
*** objcopy: aarch64-poky-linux-objcopy. Stop.

Which should be doing the job.

Are you building arm on arm ? or something else like that ?

Bruce

TOOLCHAIN = "gcc"

diff --git a/meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb b/meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb
index 87b7d240f51a..2d73e8093c2e 100644
--- a/meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb
+++ b/meta/recipes-kernel/make-mod-scripts/make-mod-scripts_1.0.bb
@@ -25,7 +25,7 @@ EXTRA_OEMAKE = " HOSTCC="${BUILD_CC} ${BUILD_CFLAGS} ${BUILD_LDFLAGS}" HOSTCPP="
do_configure() {
unset CFLAGS CPPFLAGS CXXFLAGS LDFLAGS
for t in prepare scripts_basic scripts; do
- oe_runmake CC="${KERNEL_CC}" LD="${KERNEL_LD}" AR="${KERNEL_AR}" \
+ oe_runmake CC="${KERNEL_CC}" LD="${KERNEL_LD}" AR="${KERNEL_AR}" OBJCOPY="${KERNEL_OBJCOPY}"\
-C ${STAGING_KERNEL_DIR} O=${STAGING_KERNEL_BUILDDIR} $t
done
}
--
2.31.0

--
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