Debugging a WIP PCI/ACPI patch: Bad tailq NEXT(0xffffffff81cde660->tqh_last) != NULL

Mark Johnston markj at
Thu Dec 31 15:25:53 UTC 2020

On Wed, Dec 30, 2020 at 06:10:11PM -0800, Neel Chauhan wrote:
> I have attached two files:
>   * pcidump: A dump of `pciconf -lv`
>   * acpidump: A dump of `acpidump`
> Hope this can help.
> -Neel
> On 2020-12-30 14:36, Neel Chauhan wrote:
> > Mark, thank you so much for your help!
> > 
> > However, I am getting an issue with `pci_read_device()` where it
> > returns a `vid` (PCI Vendor ID) of 0xffff.
> > 
> > This ends up returning "Cannot allocate dinfo!" from vmd.
> > 
> > Log (via grep):
> > 
> > What usually causes this?
> > 
> > I'm no expert on PC hardware, my $DAYJOB is not related to hardware
> > (I'm a C#/.NET developer for a living).
> > 
> > I do however want my Spectre running FreeBSD and am willing to write
> > patches (to some extent at least).

Hi Neel,

In the future please avoid posting to multiple threads on the same

I'm not sure what the problem is here.  I cc'ed Doug, the author of the
driver, to see if he can help.  For context, the goal is to add support
for a new device (ID 0x9a0b) to vmd(4), but vmd_bus_attach() fails with
the aforementioned error.  We found a minor bug already in that
vmd_attach() does not call rman_fini() in error paths, but I don't know
enough about vmd to usefully comment further.

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