Hi Andrew. Thanks. Yes, I understand and agree with your point. All I point is there is no universally-agreed/“standard” approach to resolve OS-BIOS interaction wrt to shared variable storage & universally agreed interface between BIOS-OS for such scenario could aid OS agnostic firmware solution. You are suggesting that be implementation details beyond the scope of UEFI spec & I agree. The reason I raised here is due to only known forum where all relevant parties engages & I liked to probe if this is common issue for broader vendor-bios-os to seek consensus on common solution, or each come up with their own unique implementation
Thanks again -Alok From: Andrew Fish [mailto:[email protected]] Sent: Friday, October 31, 2014 12:24 PM To: [email protected] Subject: Re: [edk2] Non-Volatile Variable Storage On Oct 31, 2014, at 7:58 AM, Pant, Alok <[email protected]<mailto:[email protected]>> wrote: >> 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? The UEFI spec describes how to write EFI Runtime Services that are callable via an OS provided virtual address space. The UEFI does not speak to what hardware is used to implement the backing store. The reality of how the OS and Firmware work is the variable store needs to be a resource owned by the firmware, on a lot of PC like platforms this is the NOR flash that EFI booted out of. To utilize a shared resource would require cooperation between the driver (and maybe the OS) and firmware. The UEFI spec avoids discussing OS specifics, and trying to recommend hardware implementations (as hardware changes at a rapid rate). Thanks, Andrew Fish From: Olivier Martin [mailto:[email protected]] Sent: Friday, October 31, 2014 9:04 AM To: [email protected]<mailto:[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. ------------------------------------------------------------------------------ _______________________________________________ edk2-devel mailing list [email protected]<mailto:[email protected]> https://lists.sourceforge.net/lists/listinfo/edk2-devel
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