Re: [BUG] mtdinfo -a: Tries to open NULL pointer for NOR with Eraseblock Regions

[Brian Foster <brian.foster@maxim-ic.com>]

On Saturday 06 August 2011 02:09:04 Brian Norris wrote:
> On Thu, Aug 4, 2011 at 3:41 PM, Mike Frysinger <vapier@gentoo.org> wrote:
> > On Thu, Aug 4, 2011 at 10:46, Brian Norris wrote:
>[...]
> >> Anyway, since I don't have these types of flash readily
> >> available, I don't even use these options :) And apparently,
> >> one of the biggest contributors for mtd-utils, Mike Frysinger,
> >> doesn't use region_info either...
> > 
> > i dont think any of the flashes (parallel nor, spi nor,
> > nand, etc...) included region_info.  that's why the func
> > print_region_info() sets up a dummy region_info struct that
> > describes the entire flash before calling print_region_map().
> 
> I don't know much about this, but what's the feature for
> if no one uses it?

 I'm also uncertain why Flash manufacturers have
 this “feature”, but some certainly do.  Below's
 the output of ‘mtd_debug info /dev/mtd0’ for
 two different NOR-Flash chips (on different
 reference systems).  In both cases, ‘/dev/mtd0’
 is the entire chip (an important point since
 it looks like partitions of a chip always(?)
 have zero regions?):
────────────────────────────────────────────────
# mtd_debug info /dev/mtd0    #(1) Flash from original bug report
mtd.type = MTD_NORFLASH
mtd.flags = MTD_CAP_NORFLASH
mtd.size = 33554432 (32M)
mtd.erasesize = 131072 (128K)
mtd.writesize = 1
mtd.oobsize = 0
regions = 1

region[0].offset = 0x00000000
region[0].erasesize = 131072 (128K)
region[0].numblocks = 256
region[0].regionindex = 0

# mtd_debug info /dev/mtd0    #(2) Different Flash on different system
mtd.type = MTD_NORFLASH
mtd.flags = MTD_CAP_NORFLASH
mtd.size = 4194304 (4M)
mtd.erasesize = 65536 (64K)
mtd.writesize = 1
mtd.oobsize = 0
regions = 3

region[0].offset = 0x00000000
region[0].erasesize = 8192 (8K)
region[0].numblocks = 8
region[0].regionindex = 0
region[1].offset = 0x00010000
region[1].erasesize = 65536 (64K)
region[1].numblocks = 62
region[1].regionindex = 1
region[2].offset = 0x003f0000
region[2].erasesize = 8192 (8K)
region[2].numblocks = 8
region[2].regionindex = 2
────────────────────────────────────────────────

 Our Linux systems are not explicitly taking
 advantage of multiple eraseblock regions.
 I do not know whether or not other software
 uses them.  (And yes, case ‘(2)’ really is
 only 4MiB — that chip is almost useless for
 the Linux systems.... ;-\   That system also
 has a 2nd NOR-Flash (32MiB), but I don't have
 at-hand the ‘mtd_debug info’ for it....)


cheers!
	-blf-
-- 
Brian FOSTER
Principal MTS, Software

Maxim Integrated Products (Microcontroller BU), formerly Innova Card
ZI Athélia IV - Le Forum, Bât. A
Quartier Roumagoua
13600 La Ciotat - France
Phone  : +33 (0)4 42 98 15 35
Fax    : +33 (0)4 42 08 33 19
Email  : brian.foster@maxim-ic.com
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