From: "H. Peter Anvin" <hpa@zytor.com>
To: jidong xiao <jidong.xiao@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Question on IS_ERR
Date: Thu, 09 Aug 2007 00:21:55 -0700 [thread overview]
Message-ID: <46BAC093.1000503@zytor.com> (raw)
In-Reply-To: <4104961b0708082331h4f868113g9a9e76905883619b@mail.gmail.com>
jidong xiao wrote:
> On 8/9/07, H. Peter Anvin <hpa@zytor.com> wrote:
>> No. There is no requirement that the pointer is page-aligned. The last
>> page of the address space is (in the Linux kernel) invalid by
>> definition, so there are in effect three kinds of pointers in the Linux
>> kernel: valid pointers, NULL, and ERR_PTR()s.
>>
>> -hpa
>>
>
> Regarding "The last page of the address space is invalid by definition",
> I am wondering why do we define the last page as invalid.
> The reason for defining this is just because we want to take use of
> the error number handling?
>
Pretty much.
-hpa
prev parent reply other threads:[~2007-08-09 7:22 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-08-09 5:36 Question on IS_ERR jidong xiao
2007-08-09 6:13 ` H. Peter Anvin
2007-08-09 6:31 ` jidong xiao
2007-08-09 7:21 ` H. Peter Anvin [this message]
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