Hi! this one is easy :)

For printing pointer in kernel space, you should use %px  not %p as format specifier. I heard this is for security reason(?).

Chan Kim

내 Galaxy에서 보냄

-------- 원본 이메일 --------

발신: wuzhouhui <wuzhouhui14@mails.ucas.ac.cn>

날짜: 21/8/19 오후 9:17 (GMT+09:00)

받은 사람: Lloyd <lloydkl.tech@gmail.com>, kernelnewbies@kernelnewbies.org

제목: Re: kmalloc - Address is not consecutive

On 8/19/21 6:54 PM, Lloyd wrote:
> Hi,
>
> I am trying to print the address of consecutive locations in a
> memory allocated using kmalloc. It prints non contiguous addresses! I
> tried with kmalloc_array, and  normal array on stack, I got the same 
> result. May I know the reason? The code fragment for array and result
> are given below.
>
> uint8_t MyArray[100]={'0'};
> printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[0]);
> printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[1]);
> printk(KERN_INFO "\nAddress is-> %p\n",&MyArray[2]);
>
>
> [ 8684.613909]               Address is-> 00000000b3330991
> [ 8684.613914]               Address is-> 000000000519068c
> [ 8684.613915]               Address is-> 00000000e448ca76
>
Quoted from Documentation/core-api/printk-formats.rst:
> A raw pointer value may be printed with %p which will hash the address
> before printing. The kernel also supports extended specifiers for printing
> pointers of different types.
So the address printed neither logical nor physical address.

> Thanks a lot,
>   Lloyd
>
>
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> Kernelnewbies@kernelnewbies.org
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