[U-Boot] u-boot stack overwrites end ramdisk

[Norbert van Bolhuis <nvbolhuis@aimvalley.nl>]

I was not totally correct.
gunzip/inflate has nothing to do with this problem.

the problem is this:

- do_bootm->bootm_start->arch_lmb_reserve
   reserves "unused" memory as in cur_sp-1k upto end-of-mem
   in my case this is 0x0fb0cb28 - 0x10000000

- do_bootm->do_bootm_linux->boot_body_linux->boot_ramdisk_high
   places ramdisk as close to (and below) the "unused" memory
   reservation (0x1000 aligned)
   in my case ramdisk is copied to 0x0f8c0000 - 0x0fb0ca24

- the end of the ramdisk is overwritten while printing
   "Loading Device Tree to 00ffa000, end 00fff593 ... OK"
   this happens from:
   do_bootm->do_bootm_linux->boot_relocate_fdt->printf->vsprintf->number

bootm_start and arch_lmb_reserve together use 40 + 32 = 72 bytes stack.
The assumption that u-boots' stack usage will not exceed
arch_lmb_reserve stack pointer - 1k is simply incorrect.
The "do_bootm_linux->boot_relocate_fdt->printf->vsprintf->number"
call chain (called from that same do_bootm) uses
56 + 40 + 1112 + 56 + 104 = 1368 bytes

This problem will only occur with CONFIG_OF_LIBFDT #defined
and it depends on how the 0x1000 alignment of the ramdisk image
turns out.

Btw. It looks like latest u-boot also has this problem.

I'll send a patch later making it 4k.

I do wonder why it was set so tight in the first place.