Re: GRUB on DOC: 2Mb issues

["Miguel Freitas" <miguel@cetuc.puc-rio.br>]

On 30 Aug 00, at 9:57, David Woodhouse wrote:

> doc_stage1.S could be hacked to work with both. See the existing loader
> code in the DiskOnChip firmware for inspiration.
> 
> There's no real reason to waste the second half of the pages either - and
> we could easily make the checksums work in _both_ types of device at once.

   Yes, but to not waste the second half of pages AND make 
doc_stage1.S work for all devices we would need to add code to 
identify the nand chip. I don't know how much bigger doc_stage1 
would be, but it will be probably more than 256 bytes.
   Suppose that we can fit that smart doc_stage1 in 512 bytes, so it 
will have 2 halfs of 256 bytes. Output of makecsum could be made 
as follow:
   - First half of stage1, with a checksum byte for 512 paged device, 
ie, we should only sum half each 512-page of the first 16Kb.
   - Second half of stage2 (this will NOT be loaded by IPL on 512-
page devices). checksum will be generated by summing all the first 
8Kb.
   - Second half of stage2. checksum = 0.
   - Unused 256 bytes, just to simplify stage1 (so it won't have to deal 
with READ0 / READ1 commands)
   - Stage2 from grub.


    BTW, forgot my suggestion for "loadbios" ioctl...

Regards,

Miguel Freitas



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