Guest Win7 can only be boot with small RAM when with pci passthrough device

[angela_yuan]

Hi, Nice to meet you.

We got a problem when we try to bringup guest Win7 on VirtualBox,and our host is linux12.04. The issue is that when we have a target pci passthrough device, Win7 seems can only be boot up by setting guest RAM to/under 256M, in our case. Otherwise it will crash with "Guru Meditation".

The "Info pci" shows that some of MMIO address space of pcie passthrough device is conflicting with guest RAM address space when RAM size is more than 256M. (But 256M memory is too small for our system.)

Attach is the pci info, mmio info and vbox.log. Please help to have a look.

Thanks a lot in advance. Best Regards

P.S: All AMD-V has been opened, and we don't have a problem when our guest is Linux14.04.

[angela_yuan]

OK, I have modified part of virtualbox code blindly, now I can have 1G RAM for win7. MM_RAM_HOLE_SIZE_DEFAULT 512M ->1024M

pci_bios_mem_addr start from 0xd000_0000 instead of 0xf000_0000

vga pci_set_io_region_addr from 0xc000_0000 isntead of 0xe000_0000

But I don't want to do this blindly. It seems besides RAM_HOLE_SIZE there also be a problem when the whole address space is beyond 4G.(When try to embed our passthrough device's bar to it.) Do I missed any important settings here? (Both my host and my guest OS is 64bits.)

thanks a lot. Best Regards

[Frank Mehnert]

Interesting observation. Btw, PCI passthrough is marked as 'experimental', therefore this bug is not a 'blocker'.

[aeichner]

Obsolete, PCI passthrough was removed for 6.1 and will be reintroduced in a later release.