Flash device can't find in kernel and redboot

Kevin · *nix forums Guru Joined: 24 Feb 2005 Posts: 340

hi all:
when i selected configuration entries in MTD subsystem in the process
of kernel compiling, in the "RAM/ROM/Flash chip driver" subentry, if
only I select "Support for absent chips in bus mapping" subsubentry, I
just get result such as follows:
--------------------------------------------------
sh-2.04# cat /proc/mtd
dev: size erasesize name
mtd0: 01000000 00001000 "Physically mapped flash"
--------------------------------------------------
This make me think about the flash devices had recongnized.
however:
---------------------------------------------------
sh-2.04# cat /dev/mtd0
cat: /dev/mtd0: No such device
---------------------------------------------------
It indicates that kernel has no such device. I read help of "Support
for absent chips in bus mapping" in details:
-----------------------------------------------------------
CONFIG_MTD_ABSENT:
This option enables support for a dummy probing driver used to
allocated placeholder MTD devices on systems that have socketed
or removable media. Use of this driver as a fallback chip probe
preserves the expected registration order of MTD device nodes on
the system regardless of media presence. Device nodes created
with this driver will return -ENODEV upon access.
-----------------------------------------------------------
This means regardless flash devices exist, they will always be
registered and get own device nodes, but if you want to have access to
them, which will prompt: no such device.

my flash is spansion s29GL064M, the two flashes both linked to CS1#, I
have compiled kernel many times and try many configuration entry in MTD
subsystem, but all of those always told me "Found no Physically mapped
flash device at location zero" except when I use the above
configuration --- but that's useless.
----------------------------------------------------
My typical configuration in MTD subsystem is follows:

Memory Techonology Device(MTD) support
MTD partiotioning support
Redboot partitions table parsing
Direct char device access to MTD devices
Caching block device access to MTD devices
RAM/ROM/Flash chip drivers->Detect flash chips by Common Flash
Interface(CFI) probe
RAM/ROM/Flash chip drivers->Detect non-CFI AMD/JEDEC-compatiable flash
chips
RAM/ROM/Flash chip drivers->Support for AMD/Fujitsu flash chips
Mapping drivers for chip access->CFI flash device mapping driver

OR

all of entries in "RAM/ROM/Flash chip drivers" was selected.

but the result was always:
physmap flash device 1000000 at 4000000
genprobe_new_chip called with unsupported buswidth 2
JEDEC: Found no Physically mapped flash device at location zero
priv->size is zero
genprobe_new_chip called with unsupported buswidth 2
CFI: Found no Physically mapped flash device at location zero
Physically mapped flash: Probing for AMD compatible flash...
Physically mapped flash: Found no AMD compatible device at location
zero

-----------------------------------------------------------------
In both cases I can't find my flash devices. What's wrong with them or
kernel?
Hope you can throw light on this.

Kevin · *nix forums Guru Joined: 24 Feb 2005 Posts: 340

I also want to know which driver can drive spansion flash properly?? Do
it exist?
Kevin wrote:

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