Re: [PATCH v2 2/4] ACPI: NHLT: Introduce acpi_gbl_NHLT

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

On Wed, Jul 19, 2023 at 04:47:31PM +0200, Cezary Rojewski wrote:
> On 2023-07-17 5:00 PM, Cezary Rojewski wrote:

...

> > +++ b/drivers/acpi/nhlt.c
> > @@ -0,0 +1,13 @@
> > +// SPDX-License-Identifier: GPL-2.0-only
> > +//
> > +// Copyright(c) 2023 Intel Corporation. All rights reserved.
> > +//
> > +// Authors: Cezary Rojewski <cezary.rojewski@intel.com>
> > +//          Amadeusz Slawinski <amadeuszx.slawinski@linux.intel.com>
> > +//
> > +
> > +#include <linux/export.h>
> > +#include <acpi/nhlt.h>
> > +
> > +struct acpi_table_nhlt *acpi_gbl_NHLT;
> > +EXPORT_SYMBOL_GPL(acpi_gbl_NHLT);
> 
> This approach generates a problem with undefined symbol "acpi_gbl_NHLT" when
> ACPI_NHLT is disabled. As nhlt.c is not built when said kconfig is disabled,
> symbol is never defined.
> 
> Proposed solution - modify drivers/acpi/tables.c with:
> 
> +#include <acpi/nhlt.h>
> +
> +struct acpi_table_nhlt *acpi_gbl_NHLT;
> +EXPORT_SYMBOL_GPL(acpi_gbl_NHLT);
> 
> as tables.c is always built the symbol is always there.
> The only other option I see is:
> 
> -obj-$(CONFIG_ACPI_NHLT)	+= nhlt.o
> +obj-y				+= nhlt.o
> 
> and modifying nhlt.c so it's essentially split in half with:
> #if IS_ENABLED(CONFIG_ACPI_NHLT)
> 
> but such solutions stinks. I prefer the first approach.
> What to you find guys?

I leave this to Rafael as it's his territory.

-- 
With Best Regards,
Andy Shevchenko