Use SeaBIOS as UEFI CSM

[Paul Menzel]

Dear SeaBIOS folks,

Colleagues from another institute have the problem, that the PC vendors 
started to remove the CSM (legacy BIOS) option from their UEFI firmware. 
A lot of organizations still use the CSM (legcacy BIOS) option to deploy 
their systems.

I’d like to recommend SeaBIOS to them, but I only found instruction for 
doing that with OVMF [1].

Do you know of a how-to for UEFI firmware, which is shipped on hardware? 
 From that iPXE should be started.

Kind regards,

Paul

[1]: 
https://www.seabios.org/Build_overview#Build_as_a_UEFI_Compatibility_Support...

[Roderick Klein]

Hello Paul,

I am the president of the Dutch OS/2 VOICE organisation. I have also 
kind of been lurking here look at this possibility. Instead of modiying 
legacy OS'es I was wondering if a UEFI loader could be created with 
SeaBIOS build in. I think I did ask the question once on this list but 
never got a reply. Off to work!

Something I think is very hopefull was this thread:
https://communities.intel.com/thread/51481?start=0&tstart=0

"I have FreeDOS running on Galileo using SeaBIOS as a CSM (Compatibility 
Support Module)."

I am very interested to heat the opinion of other people!
Then again what operating system do your colleagues need or use a 
virtual machine. And how many modern Linux, FreeBSD versions do not 
support UEFI ? Then again if you are running an older OS of an 
application that can be ported.

Best regards,

Roderick Klein
President os2voice.orgOn

31-10-18 07:56, Paul Menzel wrote:
> Dear SeaBIOS folks,
>
> Colleagues from another institute have the problem, that the PC vendors
> started to remove the CSM (legacy BIOS) option from their UEFI firmware.
> A lot of organizations still use the CSM (legcacy BIOS) option to deploy
> their systems.
>
> I’d like to recommend SeaBIOS to them, but I only found instruction for
> doing that with OVMF [1].
>
> Do you know of a how-to for UEFI firmware, which is shipped on hardware?
> From that iPXE should be started.
>
> Kind regards,
>
> Paul
>
> SeaBIOS mailing list
> [e-mail]
> https://mail.coreboot.org/mailman/listinfo/seabios

[Kevin O'Connor]

On Wed, Oct 31, 2018 at 07:56:26AM +0100, Paul Menzel wrote:
> Dear SeaBIOS folks,
>
> Colleagues from another institute have the problem, that the PC vendors
> started to remove the CSM (legacy BIOS) option from their UEFI firmware. A
> lot of organizations still use the CSM (legcacy BIOS) option to deploy their
> systems.
>
> I’d like to recommend SeaBIOS to them, but I only found instruction for
> doing that with OVMF [1].
>
> Do you know of a how-to for UEFI firmware, which is shipped on hardware?
> From that iPXE should be started.

To the best of my knowledge, it's not possible to add a CSM to an
existing UEFI implementation at run-time.  As far as I understand it,
the CSM capability must be compiled into it.

-Kevin

[Kevin O'Connor]

On Wed, Oct 31, 2018 at 08:17:37AM +0100, Roderick Klein wrote:
> Hello Paul,
>
> I am the president of the Dutch OS/2 VOICE organisation. I have also kind of
> been lurking here look at this possibility. Instead of modiying legacy OS'es
> I was wondering if a UEFI loader could be created with SeaBIOS build in. I
> think I did ask the question once on this list but never got a reply. Off to
> work!

To the best of my knowledge, one can't get full BIOS compatibility
from a "UEFI loader" as the BIOS really needs to be in the
0xf0000-0x100000 area of memory and that gets locked down by the
firmware.  It might be possible to "hack" SeaBIOS to run in an area of
memory outside of that range, but I suspect it would be a large amount
of work with little gain.  It would almost certainly be simpler to run
a Linux image and then launch the desired OS via QEMU.

-Kevin