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Message-ID: <940be6070604140659q31c45599wf729a47ef25103ee@mail.gmail.com>
Date: Fri, 14 Apr 2006 15:59:07 +0200
From: "Gyorgy Szekely" <hoditohod@gmail.com>
To: linux-kernel@vger.kernel.org
Subject: ramdisk driver strange behaviour
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hi,
i'm trying to use a ramdisk driver (block/rd.c) and experienced some
very strnage behaviour. In brief:
If I set ramdisk_blocksize=512 on the kernel command line, the driver
operates oddly. I execute the following commands in a shell:

mkfs.ext2 /dev/ram0     ~runs fine, no errors
mount /dev/ram0 /mnt/disk    ~doesn't mount the filesystem, can't find
it on device
mkfs.ext2 /dev/ram0     ~runs fine, same as above
mount /dev/ram0 /mnt/disk    ~mounts fine

I have to make exactly this command sequence, to make the fs usable,
eg: mkfs.ext2 twice without trying to mount doesn't work. Once the
mount succeeds everything works fine, i can read/write files,
unmount/remount everything as expected.
I copied the ramdisk contents with dd into a file, and after the first
pass it's all zeros nothing else. Like the first mkfs didn't do
anything.

If I remove the ramdisk_blocksize option from the kernel command line
(defaults to 1024) then all is ok.

Test configs:
Linux 2.6.15.2 x86 (stock kernel.org kernel)
ramdisk config: 4 ramdisks of 1024k

ucLinux 2.6.14 ARM/nommu
ramdisk config: 4 ramdisks of 1024k

George

ps: i'm not subscribet to LKML, please CC me.