ohh, it should retains value on VM reboot. // // Allocate storage for NV variables early on so it will be // at a consistent address. Since VM memory is preserved // across reboots, this allows the NV variable storage to survive // a VM reboot. //
*Thanks & RegardsRitul Guru+91-9916513186* On Mon, Feb 6, 2023 at 11:55 PM ritul guru <ritul.b...@gmail.com> wrote: > Thanks, > so as it is memory, does it mean if anything written in variable store, > and VM reboot happens then variable store will be flushed? > > > > *Thanks & RegardsRitul Guru+91-9916513186* > > > On Mon, Feb 6, 2023 at 11:47 PM Andrew (EFI) Fish <af...@apple.com> wrote: > >> >> >> On Feb 6, 2023, at 8:06 AM, ritul guru <ritul.b...@gmail.com> wrote: >> >> Hi, >> >> I have been using xen hypervisor and tianocore uefi BIOS on xen to boot >> to ubuntu OS on virtualized disk. >> and want to set a UEFI variable with UEFI runtime service SetVariable() >> to a value and the same wants to read from UEFI bootloader either >> grubx64.efi or botmgfw.efi, >> So, Is it possible to use runtime services to do such an operation for OS >> running on VM when booted with OVMF/tianocore BIOS on VM guest? >> If so, where does this variable gets stored? is it in some virtualized >> disk as there is no virtualized SPIROM available to VM. >> >> >> >> I don’t know the Xen specifics, but the firmware maps in a Flash Device >> (FD) here: >> >> [image: edk2.png] >> >> edk2/OvmfXen.fdf at master · tianocore/edk2 >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/OvmfXen.fdf> >> github.com >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/OvmfXen.fdf> >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/OvmfXen.fdf> >> >> Oh looks like it uses an emulated variable store that is just memory. See >> ReserveEmuVariableNvStore(). >> >> [image: edk2.png] >> >> edk2/Platform.c at master · tianocore/edk2 >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/XenPlatformPei/Platform.c#L365> >> github.com >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/XenPlatformPei/Platform.c#L365> >> >> <https://github.com/tianocore/edk2/blob/master/OvmfPkg/XenPlatformPei/Platform.c#L365> >> >> Thanks, >> >> Andrew Fish >> >> >> https://wiki.osdev.org/Using_UEFI_Runtime_Services_in_your_Kernel >> >> >> >> *Thanks & RegardsRitul Guru+91-9916513186* >> >> >> >> -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#99696): https://edk2.groups.io/g/devel/message/99696 Mute This Topic: https://groups.io/mt/96789290/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
