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.