ioremap and page table

ioremap and page table

[ckim]

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Hello all,

I'm almost sure but want to check if my understanding is correct.

To use a memory mapped IO, we use functions like request_mem_region and
ioremap, iounmap functions. 

I guess when we call ioremap function, the kernel sets up page table for the
region so that the region becomes non-cacheable, and I don't also have  to
worry about reordering problem. 

Is my understanding correct?

Thanks!

Chan Kim


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Re: ioremap and page table

[Deepanshu Kartikey]

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What my understanding is that ioremap converts your address to a virtual
address. So, yes everything then is handled by the kernel



On Sun, Jul 11, 2021 at 9:04 PM <ckim@etri.re.kr> wrote:

> Hello all,
>
> I’m almost sure but want to check if my understanding is correct.
>
> To use a memory mapped IO, we use functions like request_mem_region and
> ioremap, iounmap functions.
>
> I guess when we call ioremap function, the kernel sets up page table for
> the region so that the region becomes non-cacheable, and I don’t also have
>  to worry about reordering problem.
>
> Is my understanding correct?
>
> Thanks!
>
> Chan Kim
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies@kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>

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RE: ioremap and page table

[ckim]

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Ah, yes of course the virtual address. Thanks for pointing it out!

Chan Kim

 

From: Deepanshu Kartikey <kartikey406@gmail.com> 
Sent: Monday, July 12, 2021 1:48 AM
To: ckim@etri.re.kr
Cc: kernelnewbies@kernelnewbies.org
Subject: Re: ioremap and page table

 

 

What my understanding is that ioremap converts your address to a virtual address. So, yes everything then is handled by the kernel

 

 

 

On Sun, Jul 11, 2021 at 9:04 PM <ckim@etri.re.kr <mailto:ckim@etri.re.kr> > wrote:

Hello all,

I’m almost sure but want to check if my understanding is correct.

To use a memory mapped IO, we use functions like request_mem_region and ioremap, iounmap functions. 

I guess when we call ioremap function, the kernel sets up page table for the region so that the region becomes non-cacheable, and I don’t also have  to worry about reordering problem. 

Is my understanding correct?

Thanks!

Chan Kim

_______________________________________________
Kernelnewbies mailing list
Kernelnewbies@kernelnewbies.org <mailto:Kernelnewbies@kernelnewbies.org> 
https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies


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