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Date:   Mon, 9 Dec 2019 11:41:55 -0500
From:   Jeremy Cline <jcline@redhat.com>
To:     Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>
Cc:     linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: s390 depending on cc-options makes it difficult to configure
Message-ID: <20191209164155.GA78160@dev.jcline.org>
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Hi folks,

Commit 5474080a3a0a ("s390/Kconfig: make use of 'depends on cc-option'")
makes it difficult to produce an s390 configuration for Fedora and Red
Hat kernels.

The issue is I have the following configurations:

CONFIG_MARCH_Z13=3Dy
CONFIG_TUNE_Z14=3Dy
# CONFIG_TUNE_DEFAULT is not set

When the configuration is prepared on a non-s390x host without a
compiler with -march=3Dz* it changes CONFIG_TUNE_DEFAULT to y which, as
far as I can tell, leads to a kernel tuned for z13 instead of z14.
Fedora and Red Hat build processes produce complete configurations from
snippets on any available host in the build infrastructure which very
frequently is *not* s390.

I did a quick search and couldn't find any other examples of Kconfigs
depending on march or mtune compiler flags and it seems like it'd
generally problematic for people preparing configurations.

Regards,
Jeremy