Re: [Info-mtools] What does it take to support FAT12 dialects?

[Pali Rohár]

On Wednesday 19 May 2021 12:31:54 Alexander Huemer wrote:
> On Wed, May 19, 2021 at 05:10:13PM +0200, Pali Rohár wrote:
> > Hello! Is linux kernel able to mount image and access content of this
> > filesystem? Can you provide example of such image? I can look at it...
> 
> I have to admit that I didn't try before. Indeed, the kernel seems to be 
> able to mount a 1.2M image just fine! At least an `ls` shows content and 
> the md5sum of a known file is correct.

Ok, so my guess is that this 1.2M image is close-to-standard and if
mtools cannot read it, it could be some issue in mtools.

> A 2.4M image is being mounted, but `ls` shows garbage, and this is 
> ending up in the kernel ring buffer:

Just a question: Is this image clean and not corrupted? Because it does
not have valid information in FAT12/16 boot sector.

> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 0000abda)
> May 19 15:17:28 void kernel: FAT-fs (loop0): Filesystem has been set read-only
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, invalid access to FAT 
> (entry 0x00000a53)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 00007007)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 0000a389)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 000070d1)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 000070d1)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 0000129f)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 0000fdff)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 000071d1)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 000070d1)
> May 19 15:17:28 void kernel: FAT-fs (loop0): error, fat_get_cluster: invalid 
> start cluster (i_pos 0, start 0000129f)
> 
> I'll provide images off-list.

I have received them. I will try to look at it.

> Thank you!
> 
> -Alex
> 

-- 
Pali Rohár
pali.rohar@gmail.com