[meta-xilinx] FW: Kernel Command Line problem

[Michal Simek]

Hi Martin,

you are right. I have confirmed it and pushed it to xlnx_3.8 branch.
I will test the same on the master-next just for sure.
There were some changes that's why I can't just simple apply this patch there.

Thanks,
Michal

commit 3213f6447f29121d939c671116911d493538ea13
Author: Michal Simek <michal.simek at xilinx.com>
Date:   Tue Dec 10 15:59:28 2013 +0100

    microblaze: Fix passing kernel command line from bootloader

    This patch fix the problem with overwritten cmdline by
    chosen one from DT. Bootloader has a higher precedence
    than DT.

    Reported-by: Martin Townsend <martin.townsend at xsilon.com>
    Signed-off-by: Michal Simek <michal.simek at xilinx.com>


On 12/05/2013 11:26 PM, Sipke Vriend wrote:
> Hi Martin,
> 
> For Zynq your understanding would be correct, but I am unsure for
> Microblaze.
> I am forwarding this to git at xilinx.com as the team monitoring that 
> may be able to assist you.
> 
> Regards
> Sipke
> 
>> -----Original Message-----
>> From: meta-xilinx-bounces at yoctoproject.org 
>> [mailto:meta-xilinx-bounces at yoctoproject.org] On Behalf Of Martin Townsend
>> Sent: Thursday, 5 December 2013 12:57 AM
>> To: meta-xilinx at yoctoproject.org
>> Subject: [meta-xilinx] Kernel Command Line problem
>>
>> Hi,
>>
>> I now have the 3.10 Kernel booting.  I had an issue where my Kernel 
>> bootargs that I had setup in the U-Boot environment weren't being used 
>> by the Kernel.  After some debugging I found that they were being 
>> overwritten by the ones in the 'chosen' section of the device tree.  My 
>> understanding (which may be wrong) is that the bootargs passed by the 
>> bootloader have a higher precedence than the one in the device tree so I 
>> hacked the prom.c file in arch/microblaze/kernel/prom.c so it doesn't 
>> process 'chosen' to get things working.  The reason I want to use U-Boot 
>> bootargs is that we are mounting the Root Filesystem using NFS and each 
>> board will have a different rootpath variable in the U-Boot env, we are 
>> also storing the unique MAC address here too.  It's easier to program a 
>> unique environment rather than regenerate the device tree.
>>
>> First am I right in assuming the bootloader should have higher 
>> precedence and if so I would appreciate if someone could look at this 
>> patch that I'm using as a hack and advise on the right way to do it :)
>>
>> Best Regards,
>> Martin.
>>
>> diff --git a/arch/microblaze/kernel/prom.c b/arch/microblaze/kernel/prom.c
>> index 0a2c68f..bff2c75 100644
>> --- a/arch/microblaze/kernel/prom.c
>> +++ b/arch/microblaze/kernel/prom.c
>> @@ -118,7 +118,8 @@ void __init early_init_devtree(void *params)
>>       * device-tree, including the platform type, initrd location and
>>       * size, TCE reserve, and more ...
>>       */
>> -    of_scan_flat_dt(early_init_dt_scan_chosen, cmd_line);
>> +    if(cmd_line[0] == '\0')
>> +        of_scan_flat_dt(early_init_dt_scan_chosen, cmd_line);
>>
>>      /* Scan memory nodes and rebuild MEMBLOCKs */
>>      of_scan_flat_dt(early_init_dt_scan_root, NULL);
>> -- 
>> 1.8.3.2
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