| Alessandro Rubini | d5254f1 | 2009-01-24 18:10:37 +0100 | [diff] [blame] | 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 | |
| Alessandro Rubini | f7aa59b | 2009-06-22 09:18:57 +0200 | [diff] [blame] | 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 | |
| Alessandro Rubini | d5254f1 | 2009-01-24 18:10:37 +0100 | [diff] [blame] | 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. |