Hi Ilias, On Thu, Dec 21, 2023 at 6:30 AM Ilias Apalodimas <ilias.apalodi...@linaro.org> wrote: > > Hi Shantur > > On Thu, 21 Dec 2023 at 00:57, Shantur Rathore <i...@shantur.com> wrote: > > > > Hi Illias, > > > > On Wed, Dec 20, 2023 at 3:43 PM Peter Robinson <pbrobin...@gmail.com> wrote: > > > > > > On Wed, Dec 20, 2023 at 6:37 AM Ilias Apalodimas > > > <ilias.apalodi...@linaro.org> wrote: > > > > > > > > Hi Michael > > > > > > > > On Tue, 19 Dec 2023 at 14:47, Michael Walle <mwa...@kernel.org> wrote: > > > > > > > > > > Hi Mark, > > > > > > > > > > >> > Any runtime device drivers for variable storage should not be in > > > > > >> > the > > > > > >> > U-Boot runtime but live in the secure world (e.g. OP-TEE) FF-A > > > > > >> > is the > > > > > >> > new ARM protocol for talking to the secure world and hence fits > > > > > >> > into > > > > > >> > the picture. > > > > > >> > > > > > >> What if I just want a simple embedded boot stack where I don't > > > > > >> want any secure world and just want to be able to boot a COTS linux > > > > > >> distribution via EFI? > > > > > > > > > > > > That already works for many Linux distros. As long as the distro > > > > > > installs the appropriate BOOTxxx.EFI file you don't actually need to > > > > > > set any EFI variables for the OS to boot. It can't get any simpler > > > > > > than that. Of the main Linux distros it seems that only Debian > > > > > > doesn't do this. Someone should probably lobby Debian to do this as > > > > > > well as it would mean that Debian would just work on an EBBR > > > > > > compliant > > > > > > system. > > > > > > > > > > I know. Last time I checked CentOS (or was it Ubuntu?) tried to > > > > > set EFI variables and the installer just failed. Might be fixed now, > > > > > though. > > > > > > > > It's not. The error message is less scary in distros nowadays, but > > > > setting the variable for Boot0000 is still not working. That being > > > > said I have a plan to fix it for variables stored in a file, that's > > > > why we standardized the efi variable format in EBBR. > > > > Does this mean supporting SetVariableRT for files ? > > If yes, would it work without the driver model in runtime? > > Yes. > > The reasoning here is pretty simple. You can't keep alive drivers etc > for devices that the *kernel* eventually owns. The proposal is to > ignore the EFI spec and teach the kernel to write those directly. We > already do that when the variables are stored in an RPMB, we need to > figure out a decent scalable architecture for the rest. > Thanks for explaining this. It would be a good idea to provide EFI var storage info like location, offset, maxsize to linux and linux can modify vars as required.
Eg. location=espfile://u-boot-efi.vars offset=0 maxsize=-1 or location=spi://0 offset=0x3D0000 maxsize=0xFFFF Then the linux kernel is able to modify vars correctly. I think SPI might be simpler to implement vs file as there can be. many different ESP partitions on multiple drives or no ESP partition at all. Kind regards, Shantur > /Ilias > > > > Kind regards, > > Shantur
