Re: What Bios data is sent to the Bootloader/OS ?

[Rafael Machado <rafaelrodrigues.machado@gmail.com>]

Hi Igor

Nice catch.
Thanks for this idea!

Rafael Machado

On seg, 14 de ago de 2017 17:49 Igor Skochinsky <skochinsky@gmail.com>
wrote:

>
> Hi Rafael,
>
> It's certainly possible although not trivial.
> One possible approach is DUET which can emulate UEFI environment on top of
> the legacy BIOS. So you could have your legacy bootloader load DUET, which
> would in turn load and boot the UEFI-compatible OS. This page may be of
> use: http://www.rodsbooks.com/bios2uefi/index.html
>
> AFAIK GRUB already supports both BIOS and UEFI booting, so you may not
> have to do anything except set it up correctly.
>
> On Fri, Aug 11, 2017 at 3:00 PM, Rafael Machado <
> rafaelrodrigues.machado@gmail.com> wrote:
>
>> Hi everyone
>>
>> I have a question that probably some guys here can help.
>> The scenario I have, is that I need to create a OS image that must be able
>> to boot at a UEFI system (with no csm module), and at a legacy bios
>> system.
>> My fist thought is that this is not possible.
>>
>> The first thing I see that is different is the what the memory map is
>> presented to the Bootloader/OS. At legacy bios the int15/0xE820 is used,
>> and at a UEFI bios the GetMemoryMap() from the boot service is used. Is my
>> understanding correct?
>>
>> Besides that. Is there any other change that could not make it possible to
>> create a single BootloaderLoader/OS image able to boot on a UEFI BIOS(with
>> no CSM) and on a Legacy Bios ?
>>
>> I would like to create a list or arguments to talk with my client that
>> requested this, in case this is really not possible.
>>
>> The OS in this case is Linux, and the bootloader is Grub or Syslinux.
>>
>> Thanks and Regards
>> Rafael R. Machado
>>
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>
>
>
> --
> WBR, Igor
>