Replay . FlashData

The end of the Flash ROM contains system configuration information.

Header

This data is keyed off a 16-byte header ("footer" may be more appropriate) located at the very end of the flash -- 0xbfc7fff0 through 0xbfc7ffff.

Offset	Length	Description
0	4	Magic value 0x48414c4c ("HALL")
4	4	Pointer to start of first data item
8	4	Total length of data items
12	1	Checksum of data items
13	1	Unused/unknown - 0 in samples, no use found
14	1	Unused/unkonwn - 0 in samples, no use found
15	1	Checksum of first 15 bytes of header

Checksums

The checksums are bitwise inverses of bytewise checksums of the data involved -- ie:

u8 checksum(uchar * buf, size_t len)
{
  int i;
  u8 r = 0;
  for (i = 0; i < len; i++)
    r += buf[i];
  return ~r;
}

Data Block

The actual data is packed in, without regards to any byte alignment and without any padding, immediately preceeding the header -- ie, the last byte of the last data item is at 0xbfc7ffef.

Data Items

Each item is stored as:

Offset	Length	Description
0	4	Item ID
4	4	Item length
8	length given above	actual item data

Item order doesn't appear to matter, but the observed items and order is:

Item ID	Length	Meaning
9	1	FPGA type -- 1 for Gaea/4000
8	53	boot filename & flags
1	18	Unit serial number
7	4	OEM - 0
3	140	UserInfo? -- encrypted data including username & two password-looking items (or authorization hostname & password?), plus the known HTTP username:password data; in 4.3 at least 20 bytes longer & includes ISC
4	1	PTVIO enabled = 0xff

Not seen in data, but apparently possible:

Item ID	Meaning
2	Board serial number
0x444c4c4f ('DLLO')	something to do with the TL810
0x444c4c44 ('DLLD')	something to do with the TL810

-- ToddLarason - 29 Jun 2002

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