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Re: HVM virtualization?

Jaromír Doleček <> writes:

> Le lun. 2 nov. 2020 à 14:36, Greg Troxel <> a écrit :
>> I don't see that this hypothesis is supported by any evidence, compared
>> to some tiny interaction betwween netbsd and stub/qemu that leads to not
>> enabling DMA.  If you can explain why you think that, please do.
> Full dmesg would go a long way to help debug this. Can you post it, or
> point out where it was in the thread (probably I missed it).

It wasn't there; I am hearing people say that there is a problem, which
is basically that NetBSD 9 in HVM mode uses PIO and is therefore
unusably slow.  I'll see if I can get one.

> Also if you give me a simple way to reproduce it using local setup
> without additional fancy cloud software (I can do Linux Dom0 if
> needed) I might look into fixing this.

As I understand it, the following should cause the problem (and if not
that's very interesting):

  Linux dom0 that can support HVM guests

  domU configured to use a stub domain

  NetBSD 9 (presumably doesn't matter 9.0, 9.1, netbsd-9)

My guess is that when configured to just run qemu in dom0, things are
ok, and this only shows up with stub domains.

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