Nitin, Find my answers inline.
Regards, Sudhakar ________________________________ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Nitin Mahajan Sent: Friday, September 12, 2008 9:28 AM To: [email protected]; Gole, Anant Subject: RE: RBL, UBL , PSP Boot loader HI! --- On Thu, 11/9/08, Gole, Anant <[EMAIL PROTECTED]> wrote: > From: Gole, Anant <[EMAIL PROTECTED]> > Subject: RE: RBL, UBL , PSP Boot loader > To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>, > "[email protected]" > <[email protected]> > Date: Thursday, 11 September, 2008, 7:23 PM > Nitin, > > The terms are are as follows: > > 1. RBL - Rom bootloader - embedded in the chip > 2. UBL - User boot loader - NOT in the chip - RBL boots UBL > (except for NOR and UART boot modes) which boots a secondary > bootloader. There are size constraints on what RBL can boot > and since most secondary bootloaders do not fit in the size > UBL is required - provided by PSP > 3. UBoot - secondary bootloader that PSP provides - > typically used to boot linux kernel. > > When someone says PSP Bootloader it could mean either UBL > and UBoot and both are NOT in the chip - they are on the > external NOR/NAND memory. > > I assume you have seen the app note "Booting DaVinci > EVM from NAND Flash" which explains the procedure of > using UBL/uBoot: > http://focus.ti.com/lit/an/spraaa0/spraaa0.pdf > TI UBL Version: 1.12, Flash type: NAND Booting PSP Boot Loader PSPBootMode = NAND Starting NAND Copy... Initializing NAND flash... Valid MagicNum found. NAND Boot success. DONE U-Boot 1.3.1 (Jun 12 2008 - 12:21:54) So the above set of messages while booting, indicate that 1. A TI UBL version 1.12 was booted by the RBL, and the UBL was loaded from NAND? [Sudhakar] Correct. 2. "Booting PSP Boot Loader PSPBootMode = NAND" , PSP bootloader here means the U-Boot, which will also be loaded from NAND? [Sudhakar] Yes, here PSP bootloader means U-Boot and U-Boot is also stored in NAND. 3. This u-Boot inturn would load the Linux kernel from NAND? [Sudhakar] Linux Kernel may not be stored in NAND. U-Boot can download the Linux Kernel Image using tftp. Linux Kernel Image can be stored in NAND, in that case the bootargs and bootcmd has to be set correctly in U-Boot. 4. Most importantly , how will UBL know from which place on NAND to load the u-Boot? [Sudhakar] UBL is designed in a way to look for a particular magic number which is specific to any application, in this case, the application being U-Boot. Also while writing the U-Boot image to NAND; a header will be pre-pended to the image which will have the information regarding the page and block number where the u-boot image will be stored on NAND (Magic number is also part of this header). Based on this information, UBL will be able to read from NAND to RAM and start executing. and How will u-Boot know from which place to load the Linux kernel, since NAND is not a Random access device? regards -Nitin ________________________________ Get your new Email address! <http://sg.rd.yahoo.com/aa/mail/domainchoice/mail/signature/*http:/mail.promotions.yahoo.com/newdomains/aa/> Grab the Email name you've always wanted before someone else does!
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