How to change root device on L4 Linux ?

Taeung treeze.taeung at
Mon Apr 21 15:19:42 CEST 2014

Hello, Matthias :-)

Would you mind I ask you a question ?

I did not understood your answer, because I was uncertain it.
But, now I'm catching on. I'm analyzing 'L4 Re' document.

I've modified '' and 'arm-rv-eb-mc.devs' file as follows..

*vi '**'*
# vim:set ft=ioconfig:
# configuration file for io

l4linux => new System_bus()
    NIC => wrap(hw-root.NIC);
    FLASHMEMORY => wrap(hw-root.FLASHMEMORY);

*vi 'arm-rv-eb-mc.devs'*
local Hw = Io.Hw
local Res = Io.Res


   FLASHMEMORY = Hw.Device
     hid = "flashmemory";
     Res.mmio(0x02198000 , 0x0219BFFF);


   NIC = Hw.Device
     hid = "smsc911x";
     Res.mmio(0x02188000, 0x0218BFFF);

But I've failed booting with kernel commandline 
'....root=/dev/mtdblock0p1...' to set RootFilesystem as SD 

The log is ...

Added static device '(noname)' with 0 resources.
Added static device 'NIC' with 2 resources.
Added static device 'FLASHMEMORY' with 1 resources.


L4 serial driver
ttyLv0 at MMIO 0x1 (irq = 211, base_baud = 230400) is a L4
l4ser_shm: L4 shared mem serial driver
l4cdds: No name given, not starting.
brd: module loaded
l4bdds: No name given, not starting.
mousedev: PS/2 mouse device common for all mice
TCP: cubic registered
NET: Registered protocol family 17

Waiting for root device /dev/mtdblock0p1...


The log message has been stopped at 'Waiting for root device 
/dev/mtdblock0p1... '

I guess kernel command line is wrong.
Is my guess right ?

Or is '.io' , '.devs' file wrong ?

If anyone give me small hints , I would appreciate.

- Taeung -

On 04/01/2014 09:23 PM, Matthias Lange wrote:
> Hi,
> On Tue, Apr 01, 2014 at 07:07:44PM +0900, Taeung wrote:
>> Hello, L4 hackers :-)
>> I want to change *root device* on L4 Linux instead of ramdisk.
>> Root device I want is like '*/dev/mtdblock0*' or '/dev/mmcblk1p1'
>> instead of 'rom/ramdisk-arm.rd'.
>> So, I've configured somethings in 'L4 Linux menuconfig', additionally.
>> Somethings are as follows ..
>> ==============================
>> <*> MMC/SD/SDIO card support  --->
>> <*> The Extended 4 (ext4) filesystem
>>   [*]   Ext4 POSIX Access Control Lists
>>   [*]   Ext4 Security Labels
>> ==============================
>> kernel command line : "rom/vmlinuz.arm console=ttyLv0
>> root=/dev/mtdblock0 rootwait rw "
>> ==============================
>> But it is hangs at '*Waiting for root device /dev/mtdblock0...*'.
>> I've heard that the solution of this is to pass-through the physical MMC device to L4Linux.
>> Please, tell me it's concrete ways or hints about what I must study for solving this.
>> I can't even guess what the solution mean.. please.
> First you need to identify the native Linux driver for the SD controller. Then
> you need to identify all the resources (IO memory, GPIO pins, IRQs, clocks,
> ...) the driver requires. Then you need to make those resources available to
> L4Linux. Most likely you have to define a custom L4Linux ARM platform and
> create a platform file which defines all devices for it. Then the first step
> is to get the SD driver successfully pass the probe function.
> Matthias.

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