EFI loader doesn't handle md_preload (md_image) correct?

Harry Schmalzbauer freebsd at omnilan.de
Thu Jun 29 08:24:33 UTC 2017

 Bezüglich Harry Schmalzbauer's Nachricht vom 16.05.2017 18:26 (localtime):
> B
>>>> The issue is, that current UEFI implementation is using 64MB staging
>>>> memory for loading the kernel and modules and files. When the boot is
>>>> called, the relocation code will put the bits from staging area into the
>>>> final places. The BIOS version does not need such staging area, and that
>>>> will explain the difference.
>>>> I actually have different implementation to address the same problem,
>>>> but thats for illumos case, and will need some work to make it usable
>>>> for freebsd; the idea is actually simple - allocate staging area per
>>>> loaded file and relocate the bits into the place by component, not as
>>>> continuous large chunk (this would also allow to avoid the mines like
>>>> planted by hyperv;), but right now there is no very quick real solution
>>>> other than just build efi loader with larger staging size.
>>> Ic, thanks for the explanation.
>>> While not aware about the purpose of the staging area nor the
>>> consequences of enlarging it, do you think it's feasable increasing it
>>> to 768Mib?
>>> At least now I have an idea baout the issue and an explanation why
>>> reducing md_imgae to 100MB hasn't helped – still more than 64...
>>> Any quick hint where to define the staging area size highly appreciated,
>>> fi there are no hard objections against a 768MB size.
>>> -harry
>> The problem is that before UEFI Boot Services are not switched off, the memory is managed (and owned) by the firmware,
> Hmm, I've been expecting something like that (owend by firmware) ;-)
> So I'll stay with CSM for now, and will happily be an early adopter if
> you need someone to try anything (-stable mergable).

Toomas, thanks for your help so far! I'm just curious if there's news on
Was there a decision made whether kernel should be utilized to relocate
the MD image modules or the loader should be extended to handle
(x-)large staging areas?

I'd like to switch back to UEFI booting for various reasons (most
priority has consistency), but can't since it breaks md-rootfs with that
machine (the other run ESXi still).

If there's anything to test, please let me know.



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