[U-Boot] running u-boot from SDRAM
Hello,
I need to port U-Boot on the platform, consisting of master and daughter boards. Master boards runs WinCE; daughter board features SoC, based on ARM926EJ-S, on-chip SDRAM and ROM. Master launches daughter board by downloading binary image of bootcode in to the on-chip SDRAM, then does remap (i.e. 0x0 points at SDRAM) and boot loader starts off.
Therefore I'm wondering -- will U-Boot be fine with such a boot mode, usually systems start from flash (NOR or NAND), but here it's in RAM. I believe it should be OK, but just want to make sure.
Looking forward to receiving feedback from you. Thanks.
Dear Roman Mashak,
In message 40a670230809040449q23cdd0c4y5e02210111b87ee6@mail.gmail.com you wrote:
I need to port U-Boot on the platform, consisting of master and daughter boards. Master boards runs WinCE; daughter board features SoC, based on ARM926EJ-S, on-chip SDRAM and ROM. Master launches daughter board by downloading binary image of bootcode in to the on-chip SDRAM, then does remap (i.e. 0x0 points at SDRAM) and boot loader starts off.
I guess you are aware that SRDAM cannot just be used, instead it must initialized correctly before you can access it. Your master is also performing this initialization procedure, then?
Therefore I'm wondering -- will U-Boot be fine with such a boot mode, usually systems start from flash (NOR or NAND), but here it's in RAM. I believe it should be OK, but just want to make sure.
It doesn't hurt when the device where U-Boot is booting from is writable. You have to take care not to try t<F12>o re-initialize the RAM in U-Boot, though.
Best regards,
Wolfgang Denk
Hello Wolfgang,
2008/9/4 Wolfgang Denk wd@denx.de:
I guess you are aware that SRDAM cannot just be used, instead it must initialized correctly before you can access it. Your master is also performing this initialization procedure, then?
Yes, it is.
Therefore I'm wondering -- will U-Boot be fine with such a boot mode, usually systems start from flash (NOR or NAND), but here it's in RAM. I believe it should be OK, but just want to make sure.
It doesn't hurt when the device where U-Boot is booting from is writable. You have to take care not to try t<F12>o re-initialize the RAM in U-Boot, though.
This is my understanding that I have to define these optioins: CONFIG_SKIP_LOWLEVEL_INIT and CONFIG_SKIP_RELOCATE_UBOOT in order to avoid re-initialization of RAM and copying U-Boot image in to RAM.
participants (2)
-
Roman Mashak -
Wolfgang Denk