From: "Bernd Schuster" <schuster_bernd@gmx.net>
To: ecos-discuss@ecos.sourceware.org
Subject: [ECOS] redboot RAM version: cache disabled per default
Date: Sat, 09 Feb 2013 15:11:00 -0000 [thread overview]
Message-ID: <20130209151055.310290@gmx.net> (raw)
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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