Microblaze noMMU/MMU merge

Microblaze noMMU/MMU merge

[Michal Simek]

Hi All,

I would like to say your opinion about putting together Microblaze MMU
arch to noMMU version.

In C code will be #ifdef CONFIG_MMU ... #endif  or #ifndef.

Here is proposal for headers. The similar style is used in m68k but I
would like to have the same code
for both archs in main file.

#ifndef _ASM_MICROBLAZE_PAGE_H
#define _ASM_MICROBLAZE_PAGE_H

code for noMMU and MMU which is the same for both.

#ifdef __uClinux__
#include "page_no.h" -> noMMU specific
#else
#include "page_mm.h"-> MMU specific
#endif
#endif /* _ASM_MICROBLAZE_PAGE_H */


Thanks for your suggestion,
Michal



-- 
Michal Simek, Ing. (M.Eng)
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663

Re: Microblaze noMMU/MMU merge

[Paul Mundt]

On Tue, Apr 21, 2009 at 09:45:47AM +0200, Michal Simek wrote:
> I would like to say your opinion about putting together Microblaze MMU
> arch to noMMU version.
> 
> In C code will be #ifdef CONFIG_MMU ... #endif  or #ifndef.
> 
> Here is proposal for headers. The similar style is used in m68k but I
> would like to have the same code
> for both archs in main file.
> 
> #ifndef _ASM_MICROBLAZE_PAGE_H
> #define _ASM_MICROBLAZE_PAGE_H
> 
> code for noMMU and MMU which is the same for both.
> 
> #ifdef __uClinux__
> #include "page_no.h" -> noMMU specific
> #else
> #include "page_mm.h"-> MMU specific
> #endif
> #endif /* _ASM_MICROBLAZE_PAGE_H */
> 
There's really not that much code that you need to change in order to
support nommu, as long as you designed your architecture port to be
fairly compartmentalized. Take a look at some of the other architectures
in-tree that support both in the same architecture backend. sh was the
first to support a configurable CONFIG_MMU during the 2.5 days, but there
are others now as well (though I don't know how actively the others are
maintained -- nommu people tend to be even worse (!) than general
embedded people at hanging around).

In addition to sh, at least frv, m32r, and arm support a configurable
CONFIG_MMU these days. xtensa seems to have just recently joined the
club, too.

Re: Microblaze noMMU/MMU merge

[Sam Ravnborg]

On Tue, Apr 21, 2009 at 09:45:47AM +0200, Michal Simek wrote:
> Hi All,
> 
> I would like to say your opinion about putting together Microblaze MMU
> arch to noMMU version.
> 
> In C code will be #ifdef CONFIG_MMU ... #endif  or #ifndef.
> 
> Here is proposal for headers. The similar style is used in m68k but I
> would like to have the same code
> for both archs in main file.
> 
> #ifndef _ASM_MICROBLAZE_PAGE_H
> #define _ASM_MICROBLAZE_PAGE_H
> 
> code for noMMU and MMU which is the same for both.
> 
> #ifdef __uClinux__
> #include "page_no.h" -> noMMU specific
> #else
> #include "page_mm.h"-> MMU specific
> #endif
> #endif /* _ASM_MICROBLAZE_PAGE_H */

Use dedicated header files for nommu / mmu only when it is really necessary.

In headers that are _NOT_ exported you can use CONFIG_MMU to test
if you are building for MMU or not - which is more readable.
 
The reason why you cannot use CONFIG_MMU in exported headers
are that CONFIG_MMU is not valid in the userspace headers (not set/unset).

In the optimal case you have no conditionals in the exported haders
and then just use CONFIG_MMU all over.

	Sam

Re: Microblaze noMMU/MMU merge

[Michal Simek]

Sam Ravnborg wrote:
> On Tue, Apr 21, 2009 at 09:45:47AM +0200, Michal Simek wrote:
>   
>> Hi All,
>>
>> I would like to say your opinion about putting together Microblaze MMU
>> arch to noMMU version.
>>
>> In C code will be #ifdef CONFIG_MMU ... #endif  or #ifndef.
>>
>> Here is proposal for headers. The similar style is used in m68k but I
>> would like to have the same code
>> for both archs in main file.
>>
>> #ifndef _ASM_MICROBLAZE_PAGE_H
>> #define _ASM_MICROBLAZE_PAGE_H
>>
>> code for noMMU and MMU which is the same for both.
>>
>> #ifdef __uClinux__
>> #include "page_no.h" -> noMMU specific
>> #else
>> #include "page_mm.h"-> MMU specific
>> #endif
>> #endif /* _ASM_MICROBLAZE_PAGE_H */
>>     
>
> Use dedicated header files for nommu / mmu only when it is really necessary.
>
> In headers that are _NOT_ exported you can use CONFIG_MMU to test
> if you are building for MMU or not - which is more readable.
>  
> The reason why you cannot use CONFIG_MMU in exported headers
> are that CONFIG_MMU is not valid in the userspace headers (not set/unset).
>
> In the optimal case you have no conditionals in the exported haders
> and then just use CONFIG_MMU all over.
>   
ok. I'll create first proposal and you can look if is ok or not.

Thanks.
Michal

> 	Sam
>
>   


-- 
Michal Simek, Ing. (M.Eng)
PetaLogix - Linux Solutions for a Reconfigurable World
w: www.petalogix.com p: +61-7-30090663,+42-0-721842854 f: +61-7-30090663

Re: Microblaze noMMU/MMU merge

[Greg Ungerer]

Hi Michal,

Michal Simek wrote:
> I would like to say your opinion about putting together Microblaze MMU
> arch to noMMU version.
> 
> In C code will be #ifdef CONFIG_MMU ... #endif  or #ifndef.
> 
> Here is proposal for headers. The similar style is used in m68k but I
> would like to have the same code
> for both archs in main file.
> 
> #ifndef _ASM_MICROBLAZE_PAGE_H
> #define _ASM_MICROBLAZE_PAGE_H
> 
> code for noMMU and MMU which is the same for both.
> 
> #ifdef __uClinux__
> #include "page_no.h" -> noMMU specific
> #else
> #include "page_mm.h"-> MMU specific
> #endif
> #endif /* _ASM_MICROBLAZE_PAGE_H */

Breaking up the files that way is really only temporary. They will
eventually all be merged back to single files (I have probably
reworked about 60% of them so far). There ends up being very little
difference.

I would keep single files if you could.

Regards
Greg


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