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

[Jan Beulich <jbeulich@xxxxxxxx>]

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).

> 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?

Jan