[U-Boot-Users] gunzip question about large uImages

[Robin Getz]

Quick Question:
It looks to me that the max uncompressed image size is hard coded to 4Meg 
(0x400000 bytes). Any thoughts why?


Long question:
We were having some problems booting large uImages (reported here ~ month 
ago). It seemed as if the were not being decompressed properly. When we had 
someone (Aubrey Li) dig into it he found/pointed out that in the latest 
cvs, u-boot/common/cmd_bootm.c the function do_bootm defines what looks to 
be a uncompressed max length as:

    uint      unc_len = 0x400000;

This is passed to gunzip if the image needs to be uncompressed.

--snip--
	case IH_COMP_GZIP:
		printf ("   Uncompressing %s ... ", name);
		if (gunzip ((void *)ntohl(hdr->ih_load), unc_len,
			    (uchar *)data, &len) != 0) {
			puts ("GUNZIP ERROR - must RESET board to recover\n");
			SHOW_BOOT_PROGRESS (-6);
			do_reset (cmdtp, flag, argc, argv);
		}
		break;
--snip--

gunzip takes this as the second parameter and sets it to dstlen.

int gunzip(void *dst, int dstlen, unsigned char *src, unsigned long *lenp)

This is passed to the inflation routine as

        s.avail_out = dstlen;

where inflate from u-boot/lib_generic/zlib.c uses this to halt 
decompression if the image size can not fit.

-- snip -- from int inflate(z, f) --
       if (f == Z_PACKET_FLUSH && z->avail_in == 0 && z->avail_out != 0)
	  r = inflate_packet_flush(z->state->blocks);

--snip -- from local int inflate_flush(s, z, r)--
   /* compute number of bytes to copy as far as end of window */
   n = (uInt)((q <= s->write ? s->write : s->end) - q);
   if (n > z->avail_out) n = z->avail_out;
   if (n && r == Z_BUF_ERROR) r = Z_OK;

   /* update counters */
   z->avail_out -= n;
   z->total_out += n;

--

When unc_len is increased - our problem goes away...

So: two questions:
  - what is the best way to manage the size of unc_len? in 
include/configs/platform.h? Or just make it really_really big?

  - do you want a patch in u-boot/common/cmd_bootm.c/gunzip to check to see 
if the image was completely decompressed? OR
  - do you want a patch in u-boot/lib_generic/zlib.c to return an error if 
it runs out of room?

Thanks
-Robin