# VM BHYVE, Windows 2012 R2 and passthru



## TINC (May 6, 2017)

I use FBSD 11.0 and VM port. When I try to use passthru, Windows crash at boot.
bhyve.log (debug="yes"):

```
Assertion failed: (error == 0), function modify_bar_registration, file /usr/src/usr.sbin/bhyve/pci_emul.c, line 491.
fbuf frame buffer base: 0xa42800000 [sz 16777216]
```
It is possible to fix?


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## grehan@ (May 8, 2017)

A known problem - if a PCI device has 2 or more memory BARs, the bhyve PCI emulation gets a little upset at Windows setting the base address to 0xFF's to get the size while the BAR is still enabled. I have a fix for this.


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## TINC (May 9, 2017)

grehan@ said:


> I have a fix for this.


Can you share this fix?


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## grehan@ (May 16, 2017)

Still testing out the patch - will post the URL here when done.


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## aragats (May 16, 2017)

grehan@ , could be off-topic, sorry if so, is it somehow related to another common issue?
	
	



```
passthru device 0/29/0 BAR 0: base 0xdf823000 or size 0x400 not page aligned
```


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## grehan@ (May 16, 2017)

That's a different issue. Still some thought going into that one.


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## adams (Jun 23, 2017)

Hey grehan@, just wondering how that patch is coming!


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## bendany (Jan 30, 2018)

Any update? I have the same problem. ;-)


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## bendany (Mar 16, 2018)

I bought a NetXtreme BCM5722, it works very well.


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## bendany (Jan 22, 2020)

I want to passthough a sr-iov VF to windows guest, but this issue stop me. any patch I can try? thanks.


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