Re: git: 701ab6dba4a2 - main - Stop building FDT-only modules in an ACPI only kernel

From: Mitchell Horne <mhorne_at_freebsd.org>
Date: Fri, 28 Oct 2022 20:23:48 UTC 

On 10/28/22 12:59, John Baldwin wrote:
> On 10/27/22 10:59 AM, Andrew Turner wrote:
>> The branch main has been updated by andrew:
>>
>> URL: 
>> https://cgit.FreeBSD.org/src/commit/?id=701ab6dba4a2232751cd91f79bfc1d8e96bf5316
>>
>> commit 701ab6dba4a2232751cd91f79bfc1d8e96bf5316
>> Author:     Andrew Turner <andrew@FreeBSD.org>
>> AuthorDate: 2022-10-27 17:01:44 +0000
>> Commit:     Andrew Turner <andrew@FreeBSD.org>
>> CommitDate: 2022-10-27 17:59:33 +0000
>>
>>      Stop building FDT-only modules in an ACPI only kernel
>>      When building a kernel without FDT these modules don't build. As 
>> they
>>      depend on FDT and don't work with ACPI disable them.
>>      Reviewed by:    imp, kevans
>>      Sponsored by:   The FreeBSD Foundation
>>      Differential Revision: https://reviews.freebsd.org/D37178
> 
> Hmm, the OPT_FDT handling seems a bit atypical.  Other optional 
> components are
> tested for by ${KERN_OPTS:M<foo>} rather than empty(OPT_<foo>) under 
> sys/modules.
> 

Some time ago I experimented with trying to build a NOFDT kernel like 
this. I found that this type of construct worked well:

SUBDIR.${MK_FDT}= ${_allwinner} \
                   ${_if_cgem} \
                   ${_sdhci_fdt} \
                   ...

That is, use the existing SUBDIR.yes logic to conditionally exclude 
these already conditional subdirectories. It avoids multiple identical 
checks, whether you use ${KERN_OPTS:MFDT} or empty(OPT_FDT) forms. 
Something to consider.

Mitchell