Re: [microblaze-uclinux] Root file system on CF card questions...

[Mike Thompson <mpthompson@xxxxxxxxx>]

John,

Thank you for the response.  Right now I'm concentrating on just getting 
the prototype working and over time I'll work out the deeper issues of 
which uClinux filesytem would work best for a CF card.  I basically 
wanted to confirm my understanding that multiple partitions would be 
needed on a CF card -- which you did.

BTW, for anyone interested I came across the following information on 
partitioning a CF card.  I assume there are many ways of doing this, but 
this procedure seemed fairly reasonable and I'll be giving it a try.

http://www.pscience5.net/CFPartition.htm

Thanks again,

Mike Thompson


John Williams wrote:
> Hi Mike,
>
> Mike Thompson wrote:
>
> > 1. I'm assuming I can partition my 128MB CF card into two partitions. 
> > First a 16MB FAT16 partition to contain the FPGA/System Ace config 
> > files and the uClinux kernel.  Second, a 112MB Ext3 partition that can 
> > contain my root file system.  Is there a better way of going about 
> > this?  Should I use another type of file system?
>
> SystemAce has strict rules about the format of the card, in terms of the 
> first partition being FAT12 and so on.  There's not really any other way 
> to do what you propose - two partitions are required.
>
> There's a fair bit of discussion out there regarding the selection of 
> filesystems to put on compact flash.  The main concern seems to be 
> sector wear. Some higher-end CF cards do automatic wear levelling and 
> transparent mapping of logical -> physical sectors.
>
> If this is a critical application, you'll want to do some more detailed 
> research and testing.  In general, ext2 or ext3 should be fine.
>
> > 2. I created my own simple boot loader than runs in the FPGA BRAM to 
> > copy the uClinux image.bin file from the CF card in to DDR memory to 
> > run.  How would I go about passing in the kernel command line when I 
> > first jump to the kernel from my bootloader to specify an alternate 
> > root filesystem and device?
>
> This one's easy - just point r5 at a null terminated string and jump to 
> the kernel, it will do the rest.  As far as your bootloader is 
> concerned, the jump to the kernel looks like a function call with a 
> single char* argument - the command line.
>
> Regards,
>
> John
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