Re: [U-Boot] [PATCH 5/6] Support environment anywhere within erase area

Dear Guennadi Liakhovetski,

In message Pine.LNX.4.64.0808271747470.6718@axis700.grange you wrote:

This will become more important with NAND support, in which case the minimum erase region is a block, which consists of several pages and can be 256KiB large.

Please explain.

What does "anywhere" mean? At offset 0, 1, 5, 17 or 42? Or what? And what exactly is the "erase area" ?

And where's the difference between NAND and NOR flash? For NOR, the minimum "erase region" is a "block", either, which also can be 256KiB large.

• /*

• * Support environment anywhere within erase sectors: read out the
  

• * complete area to be erased, replace the environment image, write
  

• * the whole block back again.
  

• */
  

• if (DEVESIZE (dev_target) > CFG_ENV_SIZE) {

• data = malloc (DEVESIZE (dev_target));
  

• if (!data) {
  

• 	fprintf (stderr,
  

• 		 "Cannot malloc %lu bytes: %s\n",
  

• 		 DEVESIZE (dev_target),
  

• 		 strerror (errno));
  

• 	return -1;
  

• }
  

• rc = ioctl (fd_target, MEMGETINFO, &mtdinfo_target);
  

• if (rc < 0) {
  

• 	perror ("Cannot get MTD information");
  

• 	return -1;
  

• }
  

• /* Erase sector size is always a power of 2 */
  

• erase_offset = DEVOFFSET (dev_target) &
  

• 	~(mtdinfo_target.erasesize - 1);
  

• rc = flash_read_buf (dev_target, fd_target, data,
  

• 		     DEVESIZE (dev_target), erase_offset);
  

• if (rc < 0)
  

• 	return rc;
  

• /* Overwrite the old environment */
  

• memcpy(DEVOFFSET (dev_target) - erase_offset + data,
  

•        environment.image, CFG_ENV_SIZE);
  

• } else {

• data = (char *)environment.image;
  

• erase_offset = DEVOFFSET (dev_target);
  

• }

You are talking about "several pages" above. Where is this refelected in the code?

Frankly, I don't understand what you are trying to do. Please explain your implementation.

Best regards,

Wolfgang Denk