linux-kernel - RE: [PATCH 2/2] ACPICA: acpidump: Remove translation protection on integer types.

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Date:	Tue, 18 Feb 2014 00:57:29 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Luck, Tony" <tony.luck@...el.com>,
	"Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
	"Brown, Len" <len.brown@...el.com>
CC:	Lv Zheng <zetalog@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"Yu, Fenghua" <fenghua.yu@...el.com>
Subject: RE: [PATCH 2/2] ACPICA: acpidump: Remove translation protection on
 integer types.

Hi, Tony

> From: Luck, Tony
> Sent: Friday, February 14, 2014 7:35 AM
> 
> >    All definitions are equal except ACPI_UINT64_MAX for CONFIG_IA64.  It
> >    is changed from sizeof(unsigned long) to sizeof(unsigned long long).
> >    By investigation, 64bit Linux kernel build is LP64 compliant, i.e.,
> >    sizeof(long) and (pointer) are 64.  As sizeof(unsigned long) equals to
> >    sizeof(unsigned long long) on IA64 platform where CONFIG_64BIT cannot be
> >    disabled, this change actually will not affect the value of
> >    ACPI_UINT64_MAX on IA64 platforms.
> 
> This all looks correct to me - it really shouldn't make any difference
> to ia64 whether we use "long" or "long long" ... both are 8-byte entities.
> The compiler would complain in some places if you mixed & matched
> incorrectly (e.g. printk("val = %ld\n", val); will give a warning if val has
> been switched from "long" to "long long" and the format would need
> to change to "%lld").  But it looks like nothing like that happens as a
> result of this patch. All my ia64 configs build with no new warnings.
> 
> Boots OK too.

It looked scary to me that without applying this patch, Linux ACPICA was using the u64 defined by Linux but defining ACPI_UINT64_MAX to the value that could be different from sizeof(u64).
This patch can make them converged.  I was worrying about the regressions that could be triggered by this fix if there was something already dependent on this divergence.
Great to hear that there is no such dependency. :-)

Thanks and best regards
-Lv
 
> 
> -Tony
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