mount PCI-express RAM memory as block device

[Shakthi Kannan <shakstux@xxxxxxxxx>]

Greetings!

I would like to know as to how we can mount a
filesystem for RAM memory on a PCI-express card.
System for development is x86 with 2.4.22 kernel.

I, initially wrote a ramdisk driver to read/write data
between buffer and RAM. Here, I have used:
device->data = vmalloc (device->size);
where:
- device is the device driver structure variable
- data = unsigned char *
- size = unsigned int

I am able to load the above block driver and mount a
filesystem using:
dd if=/dev/zero of=/dev/sbull bs=1k count=64
mkdir /mnt/mysbull
mke2fs -vm0 /dev/sbull 64
mount /dev/sbull /mnt/mysbull

For PCI device driver, I have modifed the above to
directly ioremap device->data as follows:
device->data = ioremap_nocache (BASE_ADDRESS,
BASE_SIZE);
Have successfully done:
dd if=/dev/zero of=/dev/sbull bs=1k count=64
mkdir /mnt/mysbull
mke2fs -vm0 /dev/sbull 64

But, when I proceed to mount a filesystem, it fails. 
mount /dev/sbull /mnt/mysbull

mount:error while guessing filesystem type
mount: you must specify the filesystem type

Also, if I give "fsck -v /dev/sbull", it returns with
improper filesystem super block. Even if I specify "-t
ext2" for mount, it fails. I even tried a
loopback device mount, but it fails too:
mount -o loop /dev/sbull /mnt/mysbull

FAT: bogus logical sector size 0
VFS: Can't find a valid FAT filesystem on dev FA:00

How can I map the RAM memory on the PCI card, even
though I don't allocate any memory (during ioremap)
and display that to the end user as a mounted
filesystem so that he/she can read/write files to it?

Any help/pointers to links is appreciated.

Thanks,

K Shakthi


		
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