[people/ms/u-boot.git] / doc / README.nhk8815


The Nomadik 8815 CPU has a "secure" boot mode where no external access
(not even JTAG) is allowed.  The "remap" bits in the evaluation board
are configured in order to boot from the internal ROM memory (in
secure mode).

The boot process as defined by the manufacturer executes external code
(loaded from NAND or OneNAND) that that disables such "security" in
order to run u-boot and later the kernel without constraints. Such
code is a proprietary initial boot loader, called "X-Loader" (in case
anyone wonders, it has no relations with other loaders with the same
name and there is no GPL code inside the ST X-Loader).

SDRAM configuration, PLL setup and initial loading from NAND is
implemented in the X-Loader, so U-Boot is already running in SDRAM
when control is handed over to it.

The Makefile offers two different configurations to be used if you
boot from Nand or OneNand.

    make nhk8815_config
    make nhk8815_onenand_config

Both support OneNand and Nand. Since U-Boot, running in RAM, can't know
where it was loaded from, the configurations differ in where the filesystem
is looked for by default.


On www.st.com/nomadik and on www.stnwireless.com there are documents,
summary data and white papers on Nomadik. The full datasheet for
STn8815 is not currently available on line but under specific request
to the local ST sales offices.
Commit	Line	Data
d5254f14 AR	1
	2	The Nomadik 8815 CPU has a "secure" boot mode where no external access
	3	(not even JTAG) is allowed. The "remap" bits in the evaluation board
	4	are configured in order to boot from the internal ROM memory (in
	5	secure mode).
	6
	7	The boot process as defined by the manufacturer executes external code
	8	(loaded from NAND or OneNAND) that that disables such "security" in
	9	order to run u-boot and later the kernel without constraints. Such
	10	code is a proprietary initial boot loader, called "X-Loader" (in case
	11	anyone wonders, it has no relations with other loaders with the same
	12	name and there is no GPL code inside the ST X-Loader).
	13
	14	SDRAM configuration, PLL setup and initial loading from NAND is
	15	implemented in the X-Loader, so U-Boot is already running in SDRAM
	16	when control is handed over to it.
	17
f7aa59b2 AR	18	The Makefile offers two different configurations to be used if you
	19	boot from Nand or OneNand.
	20
	21	make nhk8815_config
	22	make nhk8815_onenand_config
	23
	24	Both support OneNand and Nand. Since U-Boot, running in RAM, can't know
	25	where it was loaded from, the configurations differ in where the filesystem
	26	is looked for by default.
	27
d5254f14 AR	28
	29	On www.st.com/nomadik and on www.stnwireless.com there are documents,
	30	summary data and white papers on Nomadik. The full datasheet for
	31	STn8815 is not currently available on line but under specific request
	32	to the local ST sales offices.