Which board is similar to mine, and how do I build a custom config?

Well... as you know I need to get that custom board running...

I read the U-BOOT readme and try to write my own config now.
Until now I just copied everything from esteem192e as it seemed most similar to my hardware to me, and renamed everything to "esm" which is the "codename" of the hardware.

Anyway, I'm not sure if there isn't a board that is more similar to mine which I missed, that's why I'm asking you:

The board will have an MPC875 at 133MHz speed.
It'll have an ethernet LXT970A PHY chip and an ISP1301 USB PHY chip for net/usb, plus a three-pin serial interface connected directly to the CPU.

The RAM will consist of 2x K4S561632E SDRAM chips (2*32MB). The 2 chips each take 16bits from the 32bit address bus, chip1 0-15, chip2 16-31. For addressing the adress lines A17-A29 connect to both chips' inputs A0-A12, address lines A6 and A7 connect to the chips' inputs BA0 and BA1.

The flash will consist of 4x AM29LV160D chips, each getting 8 bits of
the 32bit data bus, all being connected to the 21bit wide adress bus. Address bus lines A1 to A20 connect to the chips' inputs A0-A19, the chips' inputs called D15/A1 are connected to address bus line A0.

There will be more hardware available on the board, but I won't bother with that as it's not important for the task of getting that PowerPC subsystem running, I suppose.

I could send you schematic diagrams of the layout as graphics if these explanations are not explanatory enough.

The README says of u-boot says for a custom config I'll need a u-boot.lds, a flash.c, a board.c and some more things. Do I need to change anything about the u-boot.lds, the flash.c or the board.c - I hope a custom .../include/configs/ESM.h will suffice?

Enough questions for today.

Peter Asemann

Did you? So why don't you DO what you've been told there? Especially in the "Where to get help" section?

Your question is completely off topic on _this_ mailing list.

Best regards,

Wolfgang Denk

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Folks,

I am dealing with a PowerPC 7455. Here is my understanding regarding the MMU translation order: If the address is covered in a BAT, that BAT translation is in effect. If there is no BAT entry, then the page tables are used to translate the address. If there is no page table entry, an exception is thrown and the exception handler for the miss needs to add a new PTE. So, correct me if I'm wrong in my translation.

Now, The system starts up with BAT entries to get the system off the ground. I have equivalent BAT entries for the instruction and data sides. I also have the L1 I and D caches on as well as the L2 cache (I and D mode). The reason for using the BATs is to create non-cached I/O regions until the MMU PTEs are populated. Once the MMU PTEs are setup, the caches are flsuhed and disabled, the MMU is disabled, the BATS disabled, the MMU re-enabled and the caches re-enabled. So here are my questions:

1. Is it ok to have the same I and D BAT entries?
2. Is it ok to setup the initial MMU PTEs with the BATs enabled or should the caches be disabled and MMU disabled during the PTE setup?
3. Is there some other esource out there (mailing list or otherwise) that I should be addressing these questions to?

Thanks,

Jeff Domogala

regarding=20

BAT

entry,=20

I=20

Yes, the I-BAT will be used for translations on instruction fetches,=20 the D-BAT will be used on data accesses (ld/st instructions).

There should be no harm setting up MMU PTEs with BATs enabled, as you=20 said the BATs will take preference over the PTEs

This is as good as any, assuming your using linux :) Also, the=20 Freescale website has a number of App Notes on the various PPC MMUs and=20=

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