[ECOS] Re: Enabling DCACHE on GRG question. (RedBoot)

["Lars Povlsen" <lpovlsen at vitesse dot com>]

On Mon, 13 Feb 2006 02:39:14 +0200, Shmuel Vagner wrote:
> HI,
> I am running RedBoot on a GRG platform.
> I was able to compile and run both ROM and RAM versions.
> Next I tried to debug the RAM version from startup using a JTAG
debugger
> (Vison ICE II).
> It took some effort but finally I am able to debug the entire boot
> sequence.
> 
> There is only one thing that I could not get to work:
> In ixp425_misc.c hal_hardware_init() the line: HAL_DCACHE_ENABLE()
> crashes so I had to comment it out.
> I browsed through the Archives and found out that the problem is that
> the MMU is not initialized in the RAM version (It assumes that the ROM
> already did it).
> Now, the code that is responsible for MMU initializations is in
> hal_platform_setup.h _platform_setup1. The problem is that it includes
a
> lot more then MMU initialization and when I invoke it on startup the
> system crashes (Probably because it includes SDRAM initialization that
> was already done by the JTAG debugger).
> 
> My question is what part from _platform_setup1 should I keep in the
RAM
> version in order to be able to work with data caches.
> Thanks
> Shmuel
<

Hi Shmuel (and list)!

I noticed your message on the ecos-discuss archive list while searching
for a solution to the same problem.

Did you get any replies (didn't find any on the archive)?

Anycase, I noticed a small notice about a scenario of how to overcome
such an issue on
http://www.ecoscentric.com/ecospro/doc/html/ecospro-ref/arm-vpb926ejs-se
tup.html and
http://www.ecoscentric.com/ecospro/doc/html/ecospro-ref/arm-vpb926ejs-co
nfig.html - they produce a ROM kinda image and load it in the SRAM (with
a JTAG). With that way you can implement the "ROM" environment, but
don't have to flash for each update. Nifty.

Of course, this depends on whether your rig has "extra" memory like
this.

Did you get other suggestions, or did you solve this yourself?

Also using a "RAM" redboot setup I was doing a board bringup and getting
fried by the missing MMU initalization. I thought I'ld just add the
CYGSEM_HAL_ENABLE_DCACHE_ON_STARTUP = 0 option to my redboot_RAM - but
no! The HAL_ICACHE_ENABLE macro in
hal/arm/arm9/var/current/include/hal_cache.h *insists* on enabling the
MMU as well. So I bomb out the same, unless I disable the ICACHE also
(or change the code)...

Does anyone have an explanation as to why HAL_ICACHE_ENABLE enables the
MMU? I know that HAL_DCACHE_ENABLE should do so, but I regard the latter
as an error, or am I missing something here?

---Lars

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