>> You will need some handshake between the OS kernel and the UEFI firmware.
As I understand there is no real “industry standard” spec for runtime nature of 
UEFI OS/BIOS access to shared eMMC controller (owned by OS level driver) and 
vendor comes with their proprietary OS level solution. Right? Is this something 
that need to be addressed (or can be addressed  handshake between os/bios?) as 
runtime UEFI variable must be supported on those UEFI OS

This may be more of UEFI spec question but since all the experts chime in this 
forum, I also hoped to probe further?

From: Olivier Martin [mailto:[email protected]]
Sent: Friday, October 31, 2014 9:04 AM
To: [email protected]
Subject: Re: [edk2] Non-Volatile Variable Storage

Something you have to be aware about Non-Volatile UEFI variables is they might 
need to be accessible when the OS is running (through UEFI runtime services).
If your OS uses the same eMMC controller to access the filesystem then you 
might have some serious issues. You will need some handshake between the OS 
kernel and the UEFI firmware.


From: Narinder Dhillon [mailto:[email protected]]
Sent: 31 October 2014 04:12
To: [email protected]<mailto:[email protected]>
Subject: [edk2] Non-Volatile Variable Storage

Hi All,

I am attempting to implement a non-volatile variable storage in an eMMC device. 
After about a week of looking around, I have come to the realization that there 
is no such feature in edk2.
Is this correct ?

Looking at 'variable' drivers, it seems that the variable storage for both 
volatile and non are assumed to be at a physically mapped location. I can try 
to load this physical address by reading the block flash device and copying its 
contents to this location before the 'variable' driver starts. I will have to 
implement some shell command to save the changed contents back to flash device.

Does this sound reasonable or is there an easier way ?

Where can I implement this driver to load the non-volatile variable store 
before 'variable' driver starts ?

Thanx.
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