If I can remember back to the original CSM spec the onboard disk devices kind
of work like this...
Run EFI code to do the device discovery. When you start up CSM (for legacy
boot) you collect the discovery info from EFI and pass it to the BIOS. For the
onboard devices the INT 13h is not a full ROM, but just a runtime shim. You
have to pass it discovery info from EFI into BIOS.
Plug in devices should executed based on platform policy. Even on a pure EFI
system you may not chose to execute the PCI ROM to boot faster. Usually a CSM
legacy boot will post all the legacy ROMs for computability reasons.
If you have both EFI & Legacy ROM active at the same time that sounds like a
bug?
Andrew Fish
On Oct 30, 2012, at 12:39 PM, Prakash, Sathya wrote:
> Thanks all for the responses.
> I am worried about device register state if platform makes alternate calls to
> legacy and UEFI optionROMs. Can any major IBV system firmware found to
> behave this way, any help on what is the EDK reference implementation
> behavior in this case?
> -Sathya
>
> From: Joe Thomas [mailto:[email protected]]
> Sent: Tuesday, October 30, 2012 9:27 AM
> To: [email protected]
> Subject: Re: [edk2] Both legacy OpROM and UEFI BSD loaded
>
> Our experience is that every platform BIOS will do it differently…
>
> Expect that both legacy and UEFI will run, that you have no control over
> which runs first, and that calls may alternate between one and the other…
>
> In other words, plan for the worst and you’ll avoid a lot of debugging
> headaches down the road…
> [One platform implemented CSM and alternated calls between legacy INT13 and
> UEFI BlockIo – really messes up the device registers when this happens… Big
> issues with boot manager on this system as well…]
>
> // Joseph Thomas
> // Principal Software Engineer
> // Dot Hill Systems
> // 2905 NorthWest Blvd., Suite 20
> // Plymouth, MN 55441
> // 763.226.2640
>
> From: Li, Elvin [mailto:[email protected]]
> Sent: Thursday, October 25, 2012 2:58 AM
> To: [email protected]
> Subject: Re: [edk2] Both legacy OpROM and UEFI BSD loaded
>
> We can run both UEFI and Legacy OpROM start in preboot, but it will bring
> potential problem as device configuration will be possibly messed up, unless
> the BIOS or UEFI/Legacy OpROM aware this. BlockIo protocol is used to access
> storage device in preboot phase, BlockIo protocol is based on either UEFI or
> Legacy OpROM, not possibly both.
>
> From: Prakash, Sathya [mailto:[email protected]]
> Sent: Thursday, October 25, 2012 2:59 PM
> To: [email protected]
> Subject: Re: [edk2] Both legacy OpROM and UEFI BSD loaded
>
> It is two ROM images loaded in flash separately. Loading into memory is not
> a problem, but if they are executed interchangeably will the initialization
> routines of OptionROM and BSD be called every time before the switch happens?
> And whether the system firmware make sure both the services will not be used
> at same time?
>
> Thanks
> Sathya
>
> From: Ramesh Raju [mailto:[email protected]]
> Sent: Wednesday, October 24, 2012 10:32 PM
> To: '[email protected]'
> Subject: Re: [edk2] Both legacy OpROM and UEFI BSD loaded
>
> Sathya,
>
> I assume that both the images are packed in single option rom. Normal case
> will be, load only one image from option rom. But it’s really depend on the
> UEFI firmware. They might loaded both the images to support both UEFI and
> Legacy OS booting.
>
> Thanks,
> Ramesh
>
> From: Prakash, Sathya [mailto:[email protected]]
> Sent: Wednesday, October 24, 2012 1:41 AM
> To: [email protected]
> Subject: [edk2] Both legacy OpROM and UEFI BSD loaded
>
> Hello All,
> In our add-on controllers we flash both UEFI and Legacy OptionROM images and
> we have seen in some platforms both legacy OpROM and UEFI BSD are loaded by
> the UEFI system firmware. Is it acceptable case and if so do the system
> firmware can have the possibility of executing either of them in a
> interchangeable way (means whether the images or just loaded in memory are
> they both get executed simulatenously?)
>
> PS: How the add on controllers has to behave for this?
> Thanks
> Sathya
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