Date: Thu, 31 Dec 2020 21:49:56 -0800 From: Neel Chauhan <neel@neelc.org> To: Doug Ambrisko <ambrisko@ambrisko.com> Cc: Mark Johnston <markj@freebsd.org>, freebsd-hackers@freebsd.org, ambrisko@freebsd.org Subject: Re: Debugging a WIP PCI/ACPI patch: Bad tailq NEXT(0xffffffff81cde660->tqh_last) != NULL Message-ID: <4f3f6a02a452f766063ae2acb060dc64@neelc.org> In-Reply-To: <20201231200744.GA95383@ambrisko.com> References: <44528336fa9168966d121bf771e1e229@neelc.org> <X%2ByzpNIclmFYgbr7@raichu> <3c9ff844e527daacd04c51f48836b57d@neelc.org> <dbcc0e54eeb0080620ee4fb6d14845fc@neelc.org> <e73228a75b8f05c83214c62ed7e1ba68@neelc.org> <X%2B3tfbxHGdiW1Kvt@raichu> <20201231200744.GA95383@ambrisko.com>
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Hi Doug,
Thank you so much for this information.
On 2020-12-31 12:07, Doug Ambrisko wrote:
> FYI, looks like this needs to be ported over from Linux:
> static char __iomem *vmd_cfg_addr(struct vmd_dev *vmd, struct pci_bus
> *bus,
> unsigned int devfn, int reg, int len)
> {
> char __iomem *addr = vmd->cfgbar +
> ((bus->number - vmd->busn_start) << 20) +
> (devfn << 12) + reg;
>
> to
> vmd_read_config
> offset = (b << 20) + (s << 15) + (f << 12) + reg;
>
> vmd_write_config(device_t dev, u_int b, u_int s, u_int f, u_int reg,
> offset = (b << 20) + (s << 15) + (f << 12) + reg;
>
> ie.
> offset = ((b - sc->vmd_bus_start) << 20) + (s << 15) + (f << 12) +
> reg;
>
> vmd_bus_start should be added to the softc as a uint8_t type and needs
> to
> be set via attach. We need range checks to make sure
> vmd_write_config/vmd_read_config doesn't read something out of range
> since it has been reduced.
One thing I noticed is that the "b" variable (which corresponds to the
Linux bus->number) is 0 (thanks to printf). This should be the bus
number if we want to attach.
If I use: "b = pci_get_bus(dev);" in the attach, b is still 0.
And that leads to a kernel panic.
> Not sure what the shadow registers do. These both seem to be new Intel
> features and Intel doc's have been minimal. Looks like Intel is doing
> a sparse map now on newer devices.
I guess Linux is our best hope. Unless the new Intel docs is the Linux
kernel source.
> I'm concerned about the Linux comment of:
> * Certain VMD devices may have a root port configuration
> option which
> * limits the bus range to between 0-127, 128-255, or 224-255
>
> since I don't see anything to limit it between 0-127 only starting
> at 0, 128 or 224, Maybe there is max of 128 busses overall?
I could be wrong, but I guess that's a typo.
> I don't have this type of HW to test things.
I can use my hardware for testing. In the worse case scenario, I can
donate an entry-level 11th Gen/TigerLake system if I have the funds
and/or can get a tax credit.
> Doug A.
-Neel
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