[ECOS] redboot RAM version: cache disabled per default

[Bernd Schuster]

Hi, 

I hope I can also ask a question about the redboot bootloader in this newsgroup. We`re using this bootloader for your ecos o/s on a mips target. 

My question is regarding the first file which will be executed running redboot bootloader in RAM mode from ddr ram: 

located int: ecos/packages/dev/flash/hal/mips/arch/current/src/vectors.s

[
la	k0,INITIAL_CONFIG0	# Set up config0 register 
mtc0	k0,config0		# to disable cache
]

Compared to the redboot RAMROM version, the cache (KO & MM value from config0 register) will be disabled by executing the above instructions. Is there any specific reason for disabling the cache running from RAM? And if there`s such a reason, where could I enable the cache after the init for example? 

Because after the bootloader is running, I want to download some files by the serial port to the ddr ram and in a second step I want to program these files into the spi flash. Regarding the spi flash, I noticed the missing cache, because it takes much longer to download the code to the flash device. If I set the KO (0x3 cache/no coh./wr-bck/wr-alloc) and MM (enable) it`s as fast as running the RAMROM bootloader version. 

best regards
Bernd


 

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