[ECOS] EDB7xxx ROM image - MMU sets ROM noncacheable

Gary Thomas gthomas@redhat.com
Mon Oct 2 15:28:00 GMT 2000


I changed this recently because it seems that the data cache cannot be explicitly
disabled on this chip once enabled.  (I'm all ears if someone else knows how to
fix this!)  Consequently, one cannot write code which manipulates the NOR FLASH
(main FLASH chips) programmatically.

On 02-Oct-2000 AshCan@aol.com wrote:
> I am running an MP3 decoder and TCP/IP with code 
> residing in from ROM.  The file, hal_platform_extras.h 
> in /hal/arm/edb7xxx/v1_3_1/include configures the ROM 
> to noncacheable.  My player was not able to keep up 
> with the data stream resulting in choppy audio playback.
> 
> Making the ROM cacheable solved the problem.  
> 
> from:
> 
> FILL_256M_SEGMENT(ROM0_PA|MMU_L1_TYPE_Section|MMU_AP_Any)
> 
> to:
> 
> FILL_256M_SEGMENT(ROM0_PA|MMU_L1_TYPE_Section|MMU_AP_Any|MMU_Bufferable|MMU_Cacheable)
> 
> Someone should either change this in the code base or make a configuration file setting.
> 
> Dan Ash
> SonicBox


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