[Intel-gfx] Need help debuging Iris Pro on Retina MBP 11.3

[Lu, Ran]

Hi guys,

I just got a Retina MBP with Iris Pro and Nvidia GT 750. The IGD works in 
OSX(Mavericks), but when I boot into Linux, the device dose not show up in 
lspci. I debugged the kernel a little, apparently when 
pci_bus_read_dev_vendor_id is called for PCI 00:2.0 (the intel gpu), it 
returns 0xffffffff instead of 0x80860d26 and kernel just dropped the device.

I can check all the registers in grub using setpci or pcidump, and they looks 
fine, the first a few bytes are 0x80860d2600070090, according to [1] 0007 means 
the device is responsive to pci access.

So I do not know how to precede from here, because kernel already dropped the 
device, I do not have access to it in linux, setpci just telling me the device 
does not exist. I do not know this is caused by some bug in the kernel or 
there are some apple black magic behind the theme. I also I wonder is there 
any low level tool I can use to activate the IGD again without going through 
the pci regs. Any help are deeply appreciated! Thanks a lot!

[1] https://01.org/linuxgraphics/sites/default/files/documentation/intel-gfx-prm-osrc-hsw-pcie-config-registers.pdf

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Best Regards,
LR