On Thursday, January 10, 2013 10:14:07 AM Juergen Beisert wrote: > Hi Yi, > > Yi Qingliang wrote: > > On Thursday, January 10, 2013 09:36:36 AM Juergen Beisert wrote: > > > Yi Qingliang wrote: > > > > I'm using barebox (based on mini2440) on my s3c2442 board, > > > > > > > > 1. flash barebox into nand: can't start normally, but can see early > > > > output on serial. > > > > 2. load it in sdram: can start normally into shell, and then I use it > > > > to boot kernel (also in sdram, also based on mini2440). > > > > the kernel hang, no output. > > > > > > > > after dig into it, I found something: add "mem=64M" into the kernel > > > > paramer, then the kernel can start. > > > > > > > > BUT: > > > > the barebox doesn't pass that paramert to kernel for mini2440, > > > > why the mini2440 kernel can start normally? > > > > > > > > how does the kernel on 2440 get the sdram size? > > > > > > There is no autodetection possible. Take a look into > > > the "arch/arm/boards/friendlyarm-mini2440/lowlevel_init.S": This is the I found it, but: md 0x48000028 48000028: 000000b2 (represents is 128) it looks like the lowlevel_init is not executed, what's the problem. > > > code which runs immediately after reset. It calls the > > > function "s3c24x0_sdram_init" from the generic part, and uses hard coded > > > values from "arch/arm/boards/friendlyarm-mini2440/config.h" to setup the > > > SDRAM controller according to the attached SDRAM type. > > > When the SDRAM is up and running, it is very easy to read back the SDRAM > > > size from the SDRAM controller's registers (which is done in the > > > function "s3c24xx_get_memory_size"). > > > > > > So you need routines which do the same job for your S3C2442 CPU. > > > > and the kernel? how does the kernel know the sdram size for mini2440? > > read the cpu register set by barebox? > > No. The bootloader forwards this information to the kernel as an ATAG or via > device tree. But this can only work, if also the bootloader knows the > correct SDRAM size! > > Regards, > Juergen _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
