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Re: Filesystem magic number

On Wed, 1 Dec 2004 23:31:12 -0800 (PST), sumit sahu
<sahusumit2001@xxxxxxxxxxx> wrote:
> 
> Hi People,
>  
> It wud be wonderful if someone could explain how the file system magic
> number works. Reading the book 'Understanding the Linux Kernel'  I learnt
> that in order to mount the root file system the kernel probes all the
> filesystem types which had been registered at build time. For all these FS
> probed a call to the read_super function specific to the FS is made to read
> the super block. But it is said that all these calls will fail except the
> one for the FS type which actually has the Root FS. This they say is
> identified by the Filesystem specific magic number. This went a way above my
> top floor.

File System's Magic numbers are simply unique integers. Ext2 File
system has magic number 0xEF53 (AFAIK).


> Secondly, can we have the filesystem code for the Root FS in a module or is
> it to be integrated into the kernel compulsarily?
>  
> Cheers 
> Sumit
>  

Yes, root file system can be compiled as a module. 
 
-- 
Manish Regmi

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