CFI detection of x16 chips in x8 mode
dg at tao-group.com
Thu Sep 14 12:45:30 EDT 2000
>> I believe it ought to be possible to persuade FlashFX to share a
>> device with jffs. The way you'd do this is to use FXFMT to create a
>> VBF volume that only uses, say, half the device. You'd then have to
>> modify the partition table in sbc_mediagx.c to reflect this; you'd
>> have three partitions: the boot partition (256kB); the VBF volume
>> (8MB); and everything else (8MB). jffs would live in /dev/mtd/3. This
>> ought to let you boot DOS on the VBF volume and then use LILO or
>> loadlin to start Linux.
>Theoretically possible. Probably better to get it to boot off the JFFS
>directly though, if you can. It'd be nice if someone with the source to the
>flashfx stuff could release a version which works on MTD devices.
The problem with booting off JFFS is that until Linux has loaded, the only
means of accessing the flash is via VBF... which doesn't understand JFFS. And
once Linux has loaded, it doesn't understand VBF.
I've managed to get a dual-personality system up and running now. It boots
ROM-DOS off the VBF partition; then I load Linux with loadlin, and it boots
off the network. Once the modules are loaded I can access the JFFS partition.
Oh, yes. While playing, I changed the start and length of the JFFS partition.
The new one still overlapped part of the old one. I mounted it without erasing
it first... and my files were still visible. Is there any way to reduce the
startup time when you first mount the file system?
>> However, there has *got* to be some better way of handling
>> partitions... the Arcom board seems to have a 256kB block at the
>> beginning of the flash for ROM extensions, so it would make sense to
>> have that as one partition. For the rest, it would seem logical that
>> since FlashFX can find the VBF volume, so could we, and so we should
>> be able to autodetect it. But does anyone know how?
>Not easy to do this in a generic manner, and deal with all possible schemes
>for splitting the devices up.
For now, it would be sufficient for the sbc_mediagx chipset driver to allocate three partitions:
0: boot partition (0-256kB)
1: VBF volume (detected)
2: everything else
After all, flash devices aren't really large enough to warrant more complex partitioning schemes. If you really need them, then waiting until there's a proper VBF driver and creating PC partitions in it would do fine.
Anyone know how FlashFX finds the VBF volume?
dg at tao-group.com
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