Hi Andrew, Shouldn't the 'variable' driver be implemented on top of say BlockIO protocol or some other protocol that actually implements the flash read/writes. Current implementation is very simple and can only be used for reads on a board with parallel NOR flash.
Thanx. On Fri, Oct 31, 2014 at 10:23 AM, Andrew Fish <[email protected]> wrote: > > On Oct 31, 2014, at 7:58 AM, Pant, Alok <[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] > <[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] > <[email protected]>] > *Sent:* 31 October 2014 04:12 > *To:* [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] > https://lists.sourceforge.net/lists/listinfo/edk2-devel > > > > > ------------------------------------------------------------------------------ > > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.sourceforge.net/lists/listinfo/edk2-devel > >
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