From mboxrd@z Thu Jan  1 00:00:00 1970
From: Juergen Gross <jgross@suse.com>
Subject: Re: [PATCH v2 2/3] x86/acpi: take rsdp address for boot params if
 available
Date: Fri, 8 Dec 2017 12:51:05 +0100
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To: Ingo Molnar <mingo@kernel.org>
Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, x86@kernel.org, boris.ostrovsky@oracle.com, hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, corbet@lwn.net, rjw@rjwysocki.net, lenb@kernel.org, linux-acpi@vger.kernel.org

On 08/12/17 12:26, Ingo Molnar wrote:
> 
> * Juergen Gross <jgross@suse.com> wrote:
> 
>> On 08/12/17 08:05, Ingo Molnar wrote:
>>>
>>> * Juergen Gross <jgross@suse.com> wrote:
>>
>> ...
>>
>>> acpi_physical_address acpi_arch_get_root_pointer(void)
>>> {
>>> 	return boot_params.hdr.acpi_rsdp_addr;
>>> }
>>>
>>> 4)
>>>
>>> Add this to arch/x86/include/asm/acpi.h:
>>>
>>> extern acpi_physical_address acpi_arch_get_root_pointer(void);
>>
>> Uuh, this leads to problems for files including <asm/acpi.h> directly:
>> acpi_physical_address won't be defined, and including <acpi/actypes.h>
>> from arch/x86/include/asm/acpi.h will lead to:
>>
>> #error unknown ACPI_MACHINE_WIDTH
>>
>> This can only be avoided by including <linux/acpi.h> from <asm/acpi.h>
>> which seems to be the wrong layering.
>>
>> So I could:
>>
>> a) modify the sources including <asm/acpi.h> to use <linux/acpi.h>
>>    instead
>> b) don't use acpi_physical_address but either u64 or unsigned long.
>> c) ?
>>
>> What would be your preference?
> 
> Would it help if you put the prototype into linux/acpi.h perhaps? It's a generic 
> facility in principle, even if only used by x86 at the moment.

Yes, that seems to work.


Thanks,

Juergen