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Date:   Tue, 19 Jul 2022 07:39:22 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
Subject: Re: [PATCH] NFSD: Remove CONFIG_SUNRPC_GSS_MODULE
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On Tue, Jul 19, 2022 at 01:27:51PM +0000, Chuck Lever III wrote:
> > CONFIG_SUNRPC_GSS_MODULE is set if SUNRPC_GSS is built as a module.
> > CONFIG_*_MODULE is Kconfig-generated magic.
> 
> I can drop this patch, but I still have questions (and I know you are
> just the messenger, you might not know the answers).
> 
> Where is this convention documented?
> 
> When would CONFIG_SUNRPC_GSS_MODULE be defined but CONFIG_SUNRPC_GSS isn't?

If .config has CONFIG_SUNRPC_GSS=y, CONFIG_SUNRPC_GSS is set, but
CONFIG_SUNRPC_GSS_MODULE is not.

If .config has CONFIG_SUNRPC_GSS=m, CONFIG_SUNRPC_GSS_MODULE is set,
but CONFIG_SUNRPC_GSS is not.

As Anna said these days we have the IS_ENABLED helper to mostly hide
this.

I have no idea if this is documented anywhere.