> On Oct 31, 2014, at 2:25 PM, Olivier Martin <[email protected]> wrote: > > At the last Linaro Connect (http://www.linaro.org/connect > <http://www.linaro.org/connect>), Grant, Ard and I started a discussion on > this topic. I explained them the design of a UEFI protocol for the handshake > between the UEFI Runtime Variable service and the OS driver I had in mind. > But the problem becomes interesting one you add the UEFI Secure Boot in the > equation... >
I was going to mention it would be possible to standardize a layout so that it is just an EFI driver pre-OS driver, and an OS driver afterwords. But the UEFI Secure Boot makes it “challenging”. Thanks, Andrew Fish > > From: Zimmer, Vincent [mailto:[email protected] > <mailto:[email protected]>] > Sent: 31 October 2014 21:07 > To: [email protected] <mailto:[email protected]> > Subject: Re: [edk2] Non-Volatile Variable Storage > > Good points on both sides. > I see UEFI Forum w/ USWG and ASWG (UEFI and ACPI spec, resp) as a place to > explore this a little further, although Fish may be right about ultimate > scope boundaries. > As such, I’ll take the action item to convey these concerns to those bodies > this upcoming week. > Vincent > > From: Pant, Alok [mailto:[email protected] <mailto:[email protected]>] > Sent: Friday, October 31, 2014 1:56 PM > To: [email protected] <mailto:[email protected]> > Subject: Re: [edk2] Non-Volatile Variable Storage > > 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] <mailto:[email protected]>] > Sent: Friday, October 31, 2014 12:24 PM > To: [email protected] <mailto:[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] > <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] > <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 > <https://lists.sourceforge.net/lists/listinfo/edk2-devel> > > ------------------------------------------------------------------------------ > _______________________________________________ > edk2-devel mailing list > [email protected] <mailto:[email protected]> > https://lists.sourceforge.net/lists/listinfo/edk2-devel > <https://lists.sourceforge.net/lists/listinfo/edk2-devel>
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