I'm not sure if I understand. U-boot pretends mmc and DataFlash are memory mapped? That sounds completely insane, especially for MMC. What happens if you insert an 8GB SD card on a 32-bit host?
There is nothing to stop U-Boot memory commands from implementing a 64 bit virtual address space. (The day that you have an 8GB Dataflash, Champagne corks will fly.Largest one today is 8 MB)
I haven't actually used DataFlash on any avr32 boards yet, but I have written an MMC driver for it and I didn't even know it could be accessed as a memory-mapped device. In fact, I can't even understand why anyone would want that --
The reason to memory map is that then it is easy to do memory commands like copy, compare etc, which you do want to do on dataflash, even though it is not fully implemented in the current mainstream. I have implemented additional functions, because they are really needed. I wrote them because it is such a pain to copy to RAM before you can compare, and I definitely do not like to have to start doing that again.
It is perfectly possible to memory map the dataflash without having a lot of ifdefs, by letting the memory commands call a driver. I believe this is the way forward.
It is easier for a user to learn a single command set to handle flash regardless of type.
MMC/SD/USB Memories have the advantage of beeing able to be read/written by the host, and this advantage makes it more natural to use a real file system.
the main usage of an MMC or SD card is to put a filesystem (usually FAT, but you can use pretty much anything) on it and use it for storage.
I guess DataFlash makes slightly more sense to access this way, but I still think the interface is totally unintuitive.
So, even though I'm technically more of a developer than a user, consider this a vote in favour of ripping the stuff out. Unless of course lots of users depend on stuff working this way. I highly doubt it since it doesn't even work properly (yes, the MMC stuff too; the mmc2info function on pxa is a total hack which only works for 32MB cards.)
Håvard
Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys - and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=D... _______________________________________________ U-Boot-Users mailing list U-Boot-Users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/u-boot-users