Re: [PATCH v2] Add a module for retrieving SMBIOS information

[Prarit Bhargava]

On 02/09/2015 10:27 AM, Rajat Jain wrote:
> Hello,
> 
>>> 1) We have a board that boots Linux and this board itself can be plugged
>> into one of different chassis types. We need to pass different parameters to
>> the kernel based on the "CHASSIS_TYPE" information that is passed by the
>> bios in the DMI / SMBIOS tables.
> 
> Actually, I had simplified the problem statement, to avoid complicating the 
> discussion. Basically, we have enhanced the grub with a "devicetree" command 
> that supplies a flattened device tree to the kernel (just like u-boot or 
> others do in embedded world).
> 
> http://www.denx.de/wiki/view/DULG/LinuxFDTBlob
> 
> However, we need to pass different flattened device tree to the kernel based 
> on different CHASSIS_TYPE. (because different chassis have different hardware 
> components, slots etc that need to be handled differently).
> 
>>>
>>
>> Whups ... somehow stripped all the cc's on my original reply.
>>
>> why isn't 1) already in the kernel itself?
> 
> I hope my problem statement clarification above makes it clearer. However, I 
> think the problem is more generic - essentially depending on the current 
> machine type, we may have to do different things on different platforms, such 
> as:
> * Loading different kernels / initrd / device tree etc.
> * Passing different kernel parameters for:
>       - different root fs mount points (root=/dev/sda[a/b/c/d]......)
>       - enabling disabling different kernel features / drivers / subsystem 
> (pci=[nocrs/use_crs]...)
>       - etc.
> 

Well I understand the request for different kernels, but 1) implies that you're
adding additional kernel parameters based on the CHASSIS type?  So I'm wondering
why you're not making some boot time decision based on the CHASSIS type instead
of a bootloader time decision.

/me is not against the patchset.  I think the idea of booting different kernels
based on the HW sounds reasonable from a administration perspective.

P.
> Thanks,
> 
> Rajat 
> 
> 
> 
>> -----Original Message-----
>> From: Prarit Bhargava [mailto:address@hidden
>> Sent: Monday, February 09, 2015 4:44 AM
>> To: David Michael
>> Cc: address@hidden; Leif Lindholm; Andrei Borzenkov; Rajat Jain; Sanjay
>> Jain; Raghuraman Thirumalairajan; Stu Grossman
>> Subject: Re: [PATCH v2] Add a module for retrieving SMBIOS information
>>
>> On 02/08/2015 01:54 PM, David Michael wrote:
>>> The following are two use cases from Rajat Jain <address@hidden>:
>>>
>>> 1) We have a board that boots Linux and this board itself can be plugged
>> into one of different chassis types. We need to pass different parameters to
>> the kernel based on the "CHASSIS_TYPE" information that is passed by the
>> bios in the DMI / SMBIOS tables.
>>>
>>
>> Whups ... somehow stripped all the cc's on my original reply.
>>
>> why isn't 1) already in the kernel itself?
>>
>> P.
>