[U-Boot-Users] Re: U-boot environment in Xilinx System ACE?
Peter Ryser
peter.ryser at xilinx.com
Fri Jul 29 23:28:11 CEST 2005
Keith,
have a look at XAPP542
(http://www.xilinx.com/bvdocs/appnotes/xapp542.pdf). We added support
for System ACE CF and IIC and are working on getting a patch completed
that goes back out into the U-Boot tree.
- Peter
Keith J Outwater wrote:
>Hi Wolfgang -
>
>wd at denx.de wrote on 07/07/2005 01:00:41 PM:
>
>
>>Dear Keith,
>>
>>in message <OFD86B567B.6DB5DBFC-ON07257037.005D553D-07257037.
>>005E4D94 at mck.us.ray.com> you wrote:
>>
>>
>>>The nature of the design requires that the Xilinx System ACE compact
>>>
>>>
>flash
>
>
>>>card be the only nonvolatile memory on the board - no plain old FLASH
>>>memory or I2C EEPROM. Therefore, I would like to store the U-Boot
>>>environment as a file on the compact flash card.
>>>
>>>
>>This has been discussed before...
>>
>>
>
>I thought as much. I just makes too much sense :)
>
>
>
>>>I have checked the latest CVS sources and it appears that no one has
>>>implemented this yet.
>>>
>>>
>>Right.
>>
>>
>>
>>>Before I take a crack at it, is anyone planning to do this or in the
>>>process of doing it? Does anyone have any advice or caveats?
>>>
>>>
>>This is not trivial to handle. The environment needs to be accessed
>>very, very early in initialization - to read the console baudrate
>>when starting the console driver. IDE / CompactFlash on the other
>>hand gets initialized much, much later, long after relocating the
>>whole stuff to RAM.
>>
>>I don't see how these two situations mix easily. Can you attach a
>>EEPROM via I2C or so?
>>
>>
>
>I would prefer to do it that way, but the hardware must not be able to
>store any data on-board. All nonvolatile storage must be "removable"
>as in physical removal.
>
>I did remember that the u-boot environment was read very early and it
>sounds like the restricted runtime environment was the reason that
>storing then environment in compact flash was not implemented.
>
>If the problem is RAM, then I can solve that by dedicating some
>internal RAM in the FPGA for stack and data. Could we also use
>the PPC405 caches?
>
>
>
>>Best regards,
>>
>>Wolfgang Denk
>>
>>
>
>
>
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