hi, list:
I've read Documentation/powerpc/booting-without-of.txt & some
documents about fdt/dtb, as booting-without-of.txt said, the
bootloader like u-boot should passing fdt as $r3, the kernel entry
(physical) address as $r4;
r3 : physical pointer to the device-tree block
(defined in chapter II) in RAM
r4 : physical pointer to the kernel itself. This is
used by the assembly code to properly disable the MMU
in case you are entering the kernel with MMU enabled
and a non-1:1 mapping.
r5 : NULL (as to differentiate with method a)
I see fdt is something like:
struct fdt_header {
uint32_t magic; /* magic word FDT_MAGIC */
uint32_t totalsize; /* total size of DT block */
uint32_t off_dt_struct; /* offset to structure */
uint32_t off_dt_strings; /* offset to strings */
uint32_t off_mem_rsvmap; /* offset to memory reserve map */
uint32_t version; /* format version */
uint32_t last_comp_version; /* last compatible version */
/* version 2 fields below */
uint32_t boot_cpuid_phys; /* Which physical CPU id we're
booting on */
/* version 3 fields below */
uint32_t size_dt_strings; /* size of the strings block */
/* version 17 fields below */
uint32_t size_dt_struct; /* size of the structure block */
};
My question is how does the kernel cmd line being passed? I know it's
possible for u-boot to patching the target uImage (assume we're using
kernel image cuImage.bamboo)'s dtb by overwrite the dtb ``chosen''
section, but I didn't find any code in u-boot trying to do this.
Even more, after the kernel is bootstraping, (assume we're using a
bamboo board), we'll run into:
static bd_t bd;
...
void platform_init(unsigned long r3, unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7)
{
CUBOOT_INIT();
bamboo_init(&bd.bi_enetaddr, &bd.bi_enet1addr);
}
...
void bamboo_init(void *mac0, void *mac1)
{
platform_ops.fixups = bamboo_fixups;
platform_ops.exit = ibm44x_dbcr_reset;
bamboo_mac0 = mac0;
bamboo_mac1 = mac1;
fdt_init(_dtb_start);
serial_console_init();
}
...
this code will assume $r3 is passed as a ``bd_t'' structure, but $r3
passed in I think it's the dtb address (not bd_t), and bamboo_init
will set the NIC wrong MAC addresses. I'm quite sure I misunderstand
something between u-boot & linux kernel, could some help me to figure
it out? Thanks in advance!
Best Regards,
Wang Baojun
_______________________________________________
U-Boot mailing list
U-Boot@lists.denx.de
http://lists.denx.de/mailman/listinfo/u-boot
