Re: [OE-core] [PATCH] module.bbclass: add HOSTCC for out-of-tree modules

["Vyacheslav Yurkov" <uvv.mail@gmail.com>]

On 01.10.2020 16:53, Bruce Ashfield wrote:
> On Thu, Oct 1, 2020 at 10:47 AM Vyacheslav Yurkov <uvv.mail@gmail.com> wrote:
>> On 01.10.2020 16:36, Bruce Ashfield wrote:
>>> We already ran into this with the main kernel flags, and we don't want
>>> to duplicate them here.
>>>
>>> Why aren't what we have in kernel.bbclass working in your scenario ?
>>>
>>> Bruce
>>>
>> Because kernel.bbclass is not pulled in into the environment of
>> out-of-tree module recipe. Should it be?
>> This can easily be checked when you do 'bitbake hello-mod -c devshell'
>> and examine $EXTRA_OEMAKE variable.
> Yes, it should be.
>
> We build out of tree modules in each autobuilder test run, so it is
> functional for the most part. I'd be interested to see the reproducing
> kernel module and build steps, so they can be built into the tests to
> catch this.
>
> But we absolutely do not want to duplicate those flags into this class.
>
> So with a reproducer, we can perhaps shuffle things around and make
> sure that both this new case and the old ones continue to work.
>
> Bruce
>
That's interesting to know. It has been easy to reproduce in 4.x kernel, 
but with 5.x in master it fails silently. So here's what you do with 5.x 
and meta-skeleton/recipes-kernel/hello-mod/hello-mod_0.1.bb module

1. Set machine to any x86, e.g. qemux86-64
2. Enable CONFIG_UNWINDER_ORC in the kernel configuration
3. Modify kernel Makefile as follows:
Vyacheslav, [01.10.20 17:01]
index 8b1d5b9017a5..e35da9f9bb75 100644
--- a/Makefile
+++ b/Makefile
@@ -1058,7 +1058,9 @@ ifdef CONFIG_STACK_VALIDATION
       echo "int main() {}" | $(HOSTCC) -xc -o /dev/null 
$(HOST_LIBELF_LIBS) -,1,0)
    ifeq ($(has_libelf),1)
      objtool_target := tools/objtool FORCE
+    $(info "Validation enabled")
    else
+    $(info "Check failed, disabling stack validation")
      SKIP_STACK_VALIDATION := 1
      export SKIP_STACK_VALIDATION
    endif

4. If HOSTCC is set properly, then you should see "Validation enabled" 
in log.do_compile of hello-mod recipe.

Any hints where autobuilder tests are? Perhaps I could take a look and 
find a way to cover this...

Vyacheslav