Re: [U-Boot] About fixup_memory_node()

11 Jan 2013


      HI ALL:
    Also we notice that following comment in arch/arm/dts/skeleton.dtsi
it says memory info will be polulated by bootloader,
is this kind of design policy/philosophy？
/*
 * Skeleton device tree; the bare minimum needed to boot; just include and
 * add a compatible value.  The bootloader will typically populate the
memory
 * node.
 */
/ {
        #address-cells = <1>;
        #size-cells = <1>;
        chosen { };
        aliases { };
        memory { device_type = "memory"; reg = <0 0>; };
};
On Fri, Jan 11, 2013 at 3:44 PM, Dennis Lan (dlan) dennis.yxun@gmail.comwrote:
...
HI Forks：
  I have question about why memory info from fdt (memory size) will be
overwritten by
 those come from u-boot source code.
function fixup_memory_node() in bootm.c
when CONFIG_OF_LIBFDT is defined, then memory node information will be
updated
says that, if I set memory 2G in fdt file, then 512M in uboot config.h,
then final fdt info will show 512M
 (you may wonder why we set 512M in uboot, but others in fdt file, because
we may have differnet boards with differnet memory size)
  Thanks
fixup_memory_node() -> fdt_fixup_memory_banks()
int fdt_fixup_memory_banks(void *blob, u64 start[], u64 size[], int banks)
{
       .....
        for (bank = 0, len = 0; bank < banks; bank++) {
                write_cell(tmp + len, start[bank], addr_cell_len);
                len += addr_cell_len;
            write_cell(tmp + len, size[bank], size_cell_len);
            len += size_cell_len;
    }

    err = fdt_setprop(blob, nodeoffset, "reg", tmp, len);


Dennis