Re: [RFC v3 0/3] Fix errors when try to build kvm selftests on specified output

[Xiaoyao Li <xiaoyao.li@intel.com>]

On 3/27/2020 4:57 AM, shuah wrote:
> On 3/25/20 9:07 PM, Xiaoyao Li wrote:
>> Hi Shuah,
>>
>> Hope you're happy with this version that I only touch KVM's Makefile.
>>
>> I attempted to build KVM selftests on a specified dir, unfortunately
>> neither    "make O=/path/to/mydir TARGETS=kvm" in 
>> tools/testing/selftests, nor
>> "make OUTPUT=/path/to/mydir" in tools/testing/selftests/kvm work.
>>
> 
> Why are you running "make OUTPUT=/path/to/mydir"
> 
> It isn't correct.

So what's the meaning of

ifeq (0,$(MAKELEVEL))
     ifeq ($(OUTPUT),)
	OUTPUT := $(shell pwd)
	DEFAULT_INSTALL_HDR_PATH := 1
     endif
endif

in lib.mk?

> 
> make O=/path/to/mydir is what you have to use. Please main Makefile
> as well for O= and KBUILD_OUTPUT usages.
> 
> Please see Documentation/dev-tools/kselftest.rst for use-cases.
> 
> make O=/path/to/mydir TARGETS=kvm is a right use-case and I can see
> it will fail to create x86_64 directory.
> 
> Let's start with the following two commands and try to fix the
> problems you are seeing.
> 
> make O=/path/to/mydir in kvm directory (this is supported,
> however, the following command from the main Makefile is
> recommended use.)

Of course we can do this, but the "O=/path/to/mydir" only has effect on 
header install, the *.o files still generated in kvm/ directory.

And kvm's INSTALL_HDR_PATH cannot find the right headers.

That's why I choose to use "OUTPUT=/somewhere"

>  From main Makefile in kernel srcdir
> make O=/path/to/mydir TARGETS=kvm

I guess "kernel srcdir" means "kselftest srcdir", i.e., 
tools/testing/selftests/ ?

Well, as I said in the first place, I tried

	make O=/path/to/mydir TARGETS=kvm

but it doesn't work. So I did some fixup, and sent out the Patches.

If the patches are wrong, please point it out and give your comments how 
to make it right.

> Also, just build isn't sufficient for you to be able to run the
> tests.
> 
> make kselftest-install O=/path/to/mydir TARGETS=kvm will generate
> run script.

This command also has the x86_64 directory not created issue.
Since it generates header files in kernel_src/usr/include, it doesn't 
have headers path issue. But as result, the kernel_src directory is not 
clean, this requires me to run "make mrproper", I *really* don't like it.