linux-kernel - Re: [PATCH v4 1/2] ACPI / ARM64: add BAD_MADT_GICC

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Date:	Tue, 07 Jul 2015 09:12:31 -0600
From:	Al Stone <ahs3@...hat.com>
To:	Will Deacon <will.deacon@....com>, Al Stone <al.stone@...aro.org>
CC:	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"lenb@...nel.org" <lenb@...nel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	"jason@...edaemon.net" <jason@...edaemon.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-acpi@...ts.linaro.org" <linaro-acpi@...ts.linaro.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>,
	"patches@...aro.org" <patches@...aro.org>
Subject: Re: [PATCH v4 1/2] ACPI / ARM64: add BAD_MADT_GICC_ENTRY() macro

On 07/07/2015 03:25 AM, Will Deacon wrote:
> On Tue, Jul 07, 2015 at 12:16:47AM +0100, Al Stone wrote:
>> From: Al Stone <al.stone@...naro.org>
>>
>> The BAD_MADT_ENTRY() macro is designed to work for all of the subtables
>> of the MADT.  In the ACPI 5.1 version of the spec, the struct for the
>> GICC subtable (struct acpi_madt_generic_interrupt) is 76 bytes long; in
>> ACPI 6.0, the struct is 80 bytes long.  But, there is only one definition
>> in ACPICA for this struct -- and that is the 6.0 version.  Hence, when
>> BAD_MADT_ENTRY() compares the struct size to the length in the GICC
>> subtable, it fails if 5.1 structs are in use, and there are systems in
>> the wild that have them.
>>
>> This patch adds the BAD_MADT_GICC_ENTRY() that checks the GICC subtable
>> only, accounting for the difference in specification versions that are
>> possible.  The BAD_MADT_ENTRY() will continue to work as is for all other
>> MADT subtables.
>>
>> This code is being added to an arm64 header file since that is currently
>> the only architecture using the GICC subtable of the MADT.  As a GIC is
>> specific to ARM, it is also unlikely the subtable will be used elsewhere.
>>
>> Fixes: aeb823bbacc2 (ACPICA: ACPI 6.0: Add changes for FADT table.)
>> Signed-off-by: Al Stone <al.stone@...aro.org>
>> ---
>>  arch/arm64/include/asm/acpi.h | 8 ++++++++
>>  1 file changed, 8 insertions(+)
> 
> Not the nicest patch I've ever seen, but if it gets things working again:
> 
>   Acked-by: Will Deacon <will.deacon@....com>
> 
> Catalin, I assume you're picking these two up for 4.2?
> 
> Will

Yeah, not my favorite either, but it does work.  This will get
cleaned up by fixing the larger problems, I believe, and then
we should be able to remove this one.  That's the plan, at any
rate.

-- 
ciao,
al
-----------------------------------
Al Stone
Software Engineer
Red Hat, Inc.
ahs3@...hat.com
-----------------------------------
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