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MMC/SD boot mode
Read block M
(M++)
CRC
OK
?
No
Yes
Magic
number OK
?
No
Yes
Write block
number M to
AIM 0x7FFC
Configure
based on
boot descriptor
Copy block N
of UBL to AIM
(N++)
CRC
OK
?
No
Yes
All
UBL blocks
coppied
?
No
Yes
Branch to UBL
entry address
No
Yes
Try MMC/SD
boot
If a failure has occured,
read next consecutive
block up to block M=24
Start searching for valid magic number block M=1.
If a failure has occured, read next consecutive
block up to M=24
When a valid UBL signature is found, the
corresponding block number (M=1, 2, 3,,,24)
will be written to the last 32 bits of ARM internal
memory (0x7FFC)
Configure the following based on boot descriptor:
- I-Cache
- Starting block of UBL
- Number of blocks of UBL - blocks will be consecutive
- Entry point address - absolute entry point address after
loading UBL
Copy N consecutive blocks of UBL to AIM until entire UBL
is copied from MMC/SD to AIM. The starting block and the
number of blocks are specified in the descriptor
M<=24
ARM ROM Boot Modes
Figure 11-10. MMC/SD Boot Mode Flow Chart
SPRUFB3 – September 2007
Boot Modes
165