Re: [Qemu-devel] [PATCH] hw/misc/blob-loader: add a generic blob loader

[Li Guang <lig.fnst@cn.fujitsu.com>]

Peter Crosthwaite wrote:
> On Mon, Jan 6, 2014 at 10:13 PM, Paolo Bonzini<pbonzini@redhat.com>  wrote:
>    
>> Il 06/01/2014 08:56, Peter Crosthwaite ha scritto:
>>      
>>>> What are the guidelines for when to use one or the other?
>>>>          
>>> "-machine firmware=" if you want to load a firmware blob in a board
>>> specific way. This if you want to place a blob in memory at an
>>> arbitrary location on reset.
>>>        
>> "-machine firmware=" is also a pretty bad design because it's not
>> extensible and doesn't apply to most boards.  We really should get
>> per-board -machine options, so that you can have a less generic name
>> than "firmware".
>>
>>      
> Then we have even more divergence in boot flow between boards. It's
> already a bit of a Zoo out there when it comes to bootloaders.
>
> We expressed dislike for the Allwinner/FEX board specific bootloader
> due it its mainline Linux non-acceptance. This generic solution
> facilitates this case among many others and the reason its able to
> achieve that goal is it has no reliance on software policy. OTOH if we
> need to do everything board specific then we need to start deciding
> software policy for each and every board. For allwinner, FEX was a
> nack, which pretty much hangs out users of that linux kernel to dry.
>
> Looking at QEMU ARM, we are in a position now where you can only boot
> systems two ways:
>
> 1: Exactly as real HW (have to use your boards bootrom, BIOS, storage
> media etc).
> 2. ARM Linux exactly to the letter of the mainline boot process.
>
> With generic tools like this device, you at least let the users do a
> few flexible things for boots that do not fit these two limited use
> cases. And the device is completely unobtrusive on existing code. If
> developers in the future come along with their weird and wonderful
> board specific bootflows that we don't like we can now tell them to
> use the generic blob loader for their bits and pieces and everybody
> wins.
>
> If anything, the boards implementing -machine firware="" should
> implement it by layer ontop of this device.
>
>
>    
agree,

further more,  "-machine firmware=" is really not generic,
we may have to deprecate it.
because if use it, every boards should do specific things for it.

Thanks!

>    
>> Paolo
>>
>>      
>
>