[coreboot] Maintain boot order for multiple EFI based OS

[Ma, Maurice]

Hi, Sibi，

Yes,  UEFI payload follows the same way as standard UEFI FW on boot order handling.   You will have to enable a NVRAM variable driver in order to maintain the boot options and order.

Current UEFI payload uses an generic emulated variable driver provided in EDK2 MdeModulePkg.   With this driver, the variable will be lost after reboot since it is stored in memory.
To  store it in NVRAM,  you will then need to develop or port a flash based variable driver, and then replace the emulated variable driver.  This part is very platform and silicon specific.

Thanks
Maurice
From: Leahy, Leroy P
Sent: Wednesday, March 22, 2017 4:51 PM
To: Sibi.Rajasekaran at dell.com; coreboot at coreboot.org; Ma, Maurice <maurice.ma at intel.com>; Agyeman, Prince <prince.agyeman at intel.com>
Subject: RE: Maintain boot order for multiple EFI based OS

Hi Maurice and Prince,

Would you please help answer the question below?

Hi Sibi,

The maintainers for the various EDK-II packages can be found in payloads/external/tianocore/tianocore/Maintainers.txt.  In your case, search for CorebootPayloadPkg.

Lee Leahy

From: coreboot [mailto:coreboot-bounces at coreboot.org] On Behalf Of Sibi.Rajasekaran at dell.com<mailto:Sibi.Rajasekaran at dell.com>
Sent: Wednesday, March 22, 2017 6:20 AM
To: coreboot at coreboot.org<mailto:coreboot at coreboot.org>
Subject: [coreboot] Maintain boot order for multiple EFI based OS

Dell - Internal Use - Confidential
Hi,

We are using the coreboot project with Intel fsp to boot the Intel Rangeley based Mohonpeak CPU. We have built the Tianocore EDK2 project and used it as the payload to bring UEFI services to this bootloader. With this payload, we are able to boot a EFI based OS successfully.

As a next step, we are looking at installing multiple EFI OS and maintaining boot order among the OS.
How is boot order maintained with UEFI payload?
Is it through EFI NVRAM variables? If so, does coreboot support NVRAM variables?

Can you please point us in the right direction.

Thanks,
Sibi
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