Hmmm...I can answer myself now. The flash programmer programs the content from TEXT_BASE to end of the u-boot image into flash start location 0x5000_0000. When u-boot boots, it relocates itself from flash to DRAM location @TEXT_BASE. I still haven't managed to bring up the board. Guess there are some GPIO pins which I have not initialized properly.
-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of Teh Kok How Sent: Wednesday, August 05, 2009 11:22 AM To: 'Wolfgang Denk'; 'Darius Augulis' Cc: u-boot@lists.denx.de Subject: Re: [U-Boot] IXP425 TEXT_BASE
Hi; I understand Wolfgang's argument but setting the TEXT_BASE to this arbitrary high address (DRAM_end - U-boot_size(_end - _start)) does not make sense. I am new to ARM arch but in PowerPC and MIPS, the TEXT_BASE is always set to the reset vector and in ARM, the reset vector is at 0 or 0xFFFF0000. I have tried both values but still failed to boot u-boot on the board....:-(
Regards, Teh
-----Original Message----- From: u-boot-bounces@lists.denx.de [mailto:u-boot-bounces@lists.denx.de] On Behalf Of Wolfgang Denk Sent: Tuesday, August 04, 2009 11:57 PM To: Darius Augulis Cc: u-boot@lists.denx.de Subject: Re: [U-Boot] IXP425 TEXT_BASE
Dear Darius Augulis,
In message 4A784702.40806@gmail.com you wrote:
No. TEXT_BASE is an absolute address.
yes, but depends on the physical RAM base and size.
Only on ARM (and other architectures that copied it's broken implementation). TEXT_BASE is an absolute address (in the boot flash) on PowerPC.
could you please explain more? why to the end of RAM?
YOu want to have a maximum of contiguous RAM available to load Linux kernel, ramdisk images etc.
for example I have 16MB RAM, base is 0x10000000. TEXT_BASE = 0x10400000. Why is better to set this to 0x10F00000 ? To have more stack and malloc memory? But U-boot will never exceed such limit? Please explain where I am wrong. Thanks!
With RAM from 0x10000000...0x10ffffff you should probably put TEXT_BASE at 0x10f80000 which then would leave you some 15 MB of contiguous RAM for your use.
With your setup you jusy have some 3+ MB below U-Boot and some 11+ MB above it. It makes not much sense to have U-Boot sitting right in the middle of precious RAM like this.
Best regards,
Wolfgang Denk