Re: [PATCH 2/3] automation: Change build script to use arch defconfig

[Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>]

On 9/26/23 2:19 AM, Jan Beulich wrote:
> On 26.09.2023 01:12, Stefano Stabellini wrote:
>> On Mon, 25 Sep 2023, Shawn Anastasio wrote:
>>> Change automation build script to call the make defconfig target before
>>> setting CONFIG_DEBUG and extra options. This fixes issues on Power where
>>> the build fails without using the ppc64_defconfig.
>>>
>>> Signed-off-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>
>>> Reported-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> Nit: Tags in chronological order please (also affects patch 1).
>
Will fix.

>> What is the problem specifically? Is the issue that CONFIG_DEBUG enabled
>> before make olddefconfig causes certain DEBUG options also to default to
>> yes, and these additional options don't work well on Power?
> 
> No, the issue is that "make olddefconfig" takes the existing .config
> without even considering the arch's default configuration that was
> specified (KBUILD_DEFCONFIG).
> 
>>> --- a/automation/scripts/build
>>> +++ b/automation/scripts/build
>>> @@ -22,7 +22,12 @@ if [[ "${RANDCONFIG}" == "y" ]]; then
>>>      # RANDCONFIG implies HYPERVISOR_ONLY
>>>      HYPERVISOR_ONLY="y"
>>>  else
>>> -    echo "CONFIG_DEBUG=${debug}" > xen/.config
>>> +    # Start off with arch's defconfig
>>> +    make -C xen defconfig
>>> +
>>> +    # Drop existing CONFIG_DEBUG and replace with value of ${debug}
>>> +    sed -i 's/^CONFIG_DEBUG=[yn]//g' xen/.config
>>> +    echo "CONFIG_DEBUG=${debug}" >> xen/.config
>>>
>>>      if [[ -n "${EXTRA_XEN_CONFIG}" ]]; then
>>>          echo "${EXTRA_XEN_CONFIG}" >> xen/.config
> 
> It never really became clear to me whether kconfig honors the first,
> last, or any random setting in a .config that it takes as input, when
> a certain option appears there more than once. The change you make
> implies it's consistently "last" - can you confirm that's the actual
> behavior of kconfig?
>

I actually tried to avoid this issue alltogether with the sed command I
added before the echo to drop any existing CONFIG_DEBUG= line.

> Jan

Thanks,
Shawn