On 12 August 2013 01:40, Guenter Roeck <li...@roeck-us.net> wrote: > On 08/11/2013 03:04 PM, Russell King - ARM Linux wrote: >> It could be that it's qemu's PCI routing is wrong - it's not the first >> time that qemu has got something wrong.
QEMU 1.5 has had its Versatile PCI routing code rewritten to correspond with the hardware (cross-tested versus Arnd Bergmann's patchset http://marc.info/?l=linux-arm-kernel&m=128707282403376&w=2 which was run on real versatilePB backplane hardware and could handle a PCI SATA card). I believe it to be correct, and I spent a fairly long time wading through the various bits of documentation and testing those kernel patches on h/w. (It also includes a back-compatibility fudge so that old kernels which assumed the old broken QEMU behaviour will continue to work; it does not attempt to fix up the problems with kernels from commit 1bc39ac5d to present which don't work properly on either QEMU or real hardware. A fixed kernel can force-disable the fudge.) http://git.qemu.org/?p=qemu.git;a=blob;f=hw/pci-host/versatile.c has the current PCI code, which includes comments about what the routing is (in particular tables at lines 321 and 340). >> Unfortunately, the PCI routing is totally undocumented, and as I >> understand >> it, there's very few backplanes out there now that finding out their real >> routing is virtually impossible. I'm loathed to change it unless someone >> can point to a definitive source of information on this. The Versatile boards have TRMs on infocenter.arm.com; the backplane's wiring is documented in the circuit diagrams which were distributed on the CD which came with the board (ie they are non-confidential information, just difficult to lay your hands on). It's also possible to just test the hardware, which is what Arnd and I did to confirm that his patchset was OK. If somebody would like to fix the kernel I am happy to locate the PCI backplane and test everything (again). I would suggest that producing some patches which work with QEMU 1.5 or later would be a good start; then we can test on h/w as confirmation before they are applied. -- PMM
