Re: Question on IS_ERR

From: H. Peter Anvin
Date: Thu Aug 09 2007 - 03:22:18 EST


jidong xiao wrote:
> On 8/9/07, H. Peter Anvin <hpa@xxxxxxxxx> 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
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