[coreboot] how to implement variable read/write variable in coreboot

Nico Huber nico.h at gmx.de
Sat Sep 30 16:23:06 CEST 2017


On 30.09.2017 16:12, Peter Stuge wrote:
> Nico Huber wrote:
>> In-flash variable format
>> ========================
>>
>> I like to keep things simple and assume that a key=value approach
>> suffices (for this layer). Though, as we have certainly to deal with
>> NOR flash chips (and their erase blocks), we can't just store things
>> in a table that would require an erase cycle for every change of a
>> variable. Here is a random proposal:
> 
> We already have a simple coreboot-native key-value store: CBFS

Well, I never looked close, but everybody kept telling me for years that
CBFS is not designed for updates.

Nico

> 
> Yes, there is some overhead with every CBFS entry, but IIRC the
> minimum alignment is 16 bytes.
> 
> Melissa, how many variables do you think are actually needed?
> 
> 
> //Peter
> 




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