is this a bug ?

Hi,
Im using 2.4.19-rmk7-pxa1, on a pxa255. Recently I mounted jffs2
as rootfs. While doing this the conventional way, I found that
it was being mounted readonly. Since I'm using M28W640 (ST flash) which needs to be unlocked upon every reboot, I thought the readonly
was because of this locking thing. So, I integrated the flash_unlock code into the mtd subsystem, but I still got the readonly mount.
After digging into init/do_mounts.c , I found root_mountflags was by default readonly, and is sent to mount_block_root("/dev/root", root_mountflags); only to be later reassigned somewhere in fs/super.c ! (s->s_flags = flags;)

The following addition to do_mounts.c , did the trick.

+ root_mountflags &= ~MS_RDONLY;
mount_block_root("/dev/root", root_mountflags);

Now jffs2 mounts nice and clean, with readwrite !

I know you guys have dropped support for 2.4.x, but just for clarification, might even help several others struggling to get jffs2 working as rootfs :)

Cheers,
Ashwin Chaugule
Embedded Systems Engineer
Aftek Infosys Ltd.
[Embedded Division]

Uurg. RTFM !

There are at least two sane ways to do that without touching the kernel code.

- Documentation/kernel-parameters.txt (hint: rootflags)
- man mount (hint: remount)

tglx

In 2.6.12-2 my cmdline is ..

CONFIG_CMDLINE="root=/dev/mtdblock1 rootfstype=jffs2 init=/bin/sh console=ttyS0,38400 mem=32M"

Jffs2 mounts just fine. No rootflags changes anywhere !

Cheers,
Ashwin

So what ? You were asking a question about 2.4.19 and you got an answer related to that. It's coded that way in the ancient, broken and obsolete 2.4.19... kernel and there are two ways to solve that without hacking the kernel code.

Where is the bug ?

tglx

Couldnt agree more. But the deadlines prohibit us from upgrading it right now. In fact I have already fired up the board with 2.6.12-2 as stated earlier, but theres still a while till I get everything we have running on it.

Well, the fact that it works without any changes in 2.6.x, and that I had to change it in 2.4. Basically, it seemed strange that rootflags is just passed in from do_mount, remains unchanged, and later reassigned to sb->flags in super.c.... seemed strange thats all. BTW I still need to find out whats done differently in 2.6.x. I'm not implying this is a jffs2 bug anywhere, I just posted this to see if anyone else observed this, since there are several others still using 2.4.19. Also, I didnt know of the cmdline way of doing this without hacking into the source. Call me a rookie if you want.

Well, now I know :)

Cheers,
Ashwin

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