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

Toomas Soome tsoome at me.com
Mon Apr 8 07:19:11 UTC 2019

Yes, I still do remember it, just need to find time to port the feature. 

Of course the root cause there is much more complicated (we can not assume to have contigous space above 1MB), but we mostly can cope...

Sent from my iPhone

> On 8 Apr 2019, at 09:44, Harry Schmalzbauer <freebsd at omnilan.de> wrote:
>> Am 16.05.2017 um 18:26 schrieb Harry Schmalzbauer:
>> Bezüglich Toomas Soome's Nachricht vom 16.05.2017 18:20 (localtime):
>>>> On 16. mai 2017, at 19:13, Harry Schmalzbauer <freebsd at omnilan.de> wrote:
>>>> Bezüglich Toomas Soome's Nachricht vom 16.05.2017 18:00 (localtime):
>>>>>> On 16. mai 2017, at 18:45, Harry Schmalzbauer <freebsd at omnilan.de
>>>>>> <mailto:freebsd at omnilan.de>> wrote:
>>>>>> Bezüglich Harry Schmalzbauer's Nachricht vom 16.05.2017 17:28 (localtime):
>>>>>>> Bezüglich Toomas Soome's Nachricht vom 16.05.2017 16:57 (localtime):
>>>>>>>>> On 16. mai 2017, at 17:55, Harry Schmalzbauer <freebsd at omnilan.de
>>>>>>>>> <mailto:freebsd at omnilan.de>> wrote:
>>>>>>>>> Hello,
>>>>>>>>> unfortunately I had some trouble with my preferred MFS-root setups.
>>>>>>>>> It seems EFI loader doesn't handle type md_image correctly.
>>>>>>>>> If I load any md_image with loader invoked by gptboot or gptzfsboot,
>>>>>>>>> 'lsmod'
>>>>>>>>> shows "elf kernel", "elf obj module(s)" and "md_image".
>>>>>>>>> Using the same loader.conf, but EFI loader, the md_image-file is
>>>>>>>>> prompted and sems to be loaded, but not registered.  There's no
>>>>>>>>> md_image
>>>>>>>>> with 'lsmod', hence it's not astonsihing that kernel doesn't attach md0
>>>>>>>>> so booting fails since there's no rootfs.
>>>>>>>>> Any help highly appreciated, hope Toomas doesn't mind beeing
>>>>>>>>> initially CC'd.
>>>>>>>>> Thanks,
>>>>>>>>> -harry
>>>>>>>> The first question is, how large is the md_image and what other
>>>>>>>> modules are loaded?
>>>>>>> Thanks for your quick response.
>>>>>>> The images are 50-500MB uncompressed (provided by gzip compressed file).
>>>>>>> Small ammount of elf modules, 5, each ~50kB.
>>>>>> On the real HW, there's vmm and some more:
>>>>>> Id Refs Address             Size Name
>>>>>> 1   46 0xffffffff80200000   16M kernel
>>>>>> 2    1 0xffffffff8121d000   86K unionfs.ko
>>>>>> 3    1 0xffffffff81233000  3.1M zfs.ko
>>>>>> 4    2 0xffffffff81545000   51K opensolaris.ko
>>>>>> 5    7 0xffffffff81552000  279K usb.ko
>>>>>> 6    1 0xffffffff81598000   67K ukbd.ko
>>>>>> 7    1 0xffffffff815a9000   51K umass.ko
>>>>>> 8    1 0xffffffff815b6000   46K aesni.ko
>>>>>> 9    1 0xffffffff815c3000   54K uhci.ko
>>>>>> 10    1 0xffffffff815d1000   65K ehci.ko
>>>>>> 11    1 0xffffffff815e2000   15K cc_htcp.ko
>>>>>> 12    1 0xffffffff815e6000  3.4M vmm.ko
>>>>>> 13    1 0xffffffffa3a21000   12K ums.ko
>>>>>> 14    1 0xffffffffa3a24000  9.1K uhid.ko
>>>>>> Providing md_image uncompressed doesn't change anything.
>>>>>> Will deploy a /usr separated rootfs, which is only ~100MB uncompressed
>>>>>> and see if that changes anything.
>>>>>> That's all I can provide, code is far beyond my knowledge...
>>>>>> -harry
>>>>> 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).
> Hello Toomas,
> thanks for your ongoing FreeBSD commits, saw your recent libstand improvements and the efiloader commit.
> Which remembers me nagging the skilled ones for my unmet needs ;-)
> I guess nobody had time to look at the MFS-root limitation with EFI vs. BIOS.
> If you have any news/plans, please share.
> The ability to boot via EFI gives a much better console experience/usability for admins, but on MFS-root system, I'm still forced to use the old loader path, because of the 64MB size limit.
> Do you think there's a chance that this will be resolved for FreeBSD?
> Thanks,
> -harry

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