Re: pci_mapreg_map and BAR from `Bus space tutorial'

[Radoslaw Kujawa <radoslaw.kujawa%c0ff33.net@localhost>]

On 6/10/20 4:30 PM, Radoslaw Kujawa wrote:
> It is more likely that something mis-compiles now (I see a ton of 
> warnings trying to build it now), or that there is a bug in 
> implementation of test device emulation, that somehow went unnoticed 
> back in 2012.

It seems that in 2018 cobalt port was switched to common MIPS bus space 
implementation. As a part of this implementation, it started to be more 
strict about verification of addresses used by device during bus_space_map.

I earlier wrote that gxemul does not emulate Cobalt firmware and that is 
true, however it seems that it does place PCI device at certain 
addresses (0x10110000) upon boot.

NetBSD attempts to reconfigure the device to use address 0x12000000. As 
a part of switch to common MIPS bus space, for cobalt, window 
0x12000000-0x14000000 was dedicated to PCI memory BARs.

For reasons still not researched thoroughly, this reconfiguration fails, 
and the device stays at original address.

So when the pci_mapreg_map is called, a MIPS MI bus_space_map is 
executed. As a part of this, translation takes place, however sanity 
check in __BS(translate) throws EINVAL, due to device being outside of 
window range.

I've worked the problem around by placing the device in gxemul at an 
exact address expected by NetBSD:

[   1.0000000] faa0 at pci0 dev 12 function 0: vendor fabc product 0001 
(rev. 0x01)
[   1.0000000] faa0: registers at 0x12000000
[   1.0000000] faa0: just checking: 1 + 2 = 3

Please try the attached gxemul patch.

Best regards,
Radoslaw

diff --git a/gxemul-current/src/devices/bus_pci.cc b/gxemul-current/src/devices/bus_pci.cc
index ce64aa0..8e7827c 100644
--- a/gxemul-current/src/devices/bus_pci.cc
+++ b/gxemul-current/src/devices/bus_pci.cc
@@ -1436,6 +1436,7 @@ PCIINIT(ati_radeon_9200_2)
 PCIINIT(faa)
 {
        uint64_t port, memaddr;
+       memaddr = 0x12000000;
        char tmpstr[200];
 
        PCI_SET_DATA(PCI_ID_REG, PCI_ID_CODE(PCI_VENDOR_FAKECARDS,
@@ -1444,7 +1445,9 @@ PCIINIT(faa)
        PCI_SET_DATA(PCI_CLASS_REG, PCI_CLASS_CODE(PCI_CLASS_PROCESSOR,
            PCI_SUBCLASS_PROCESSOR_COPROC, 0) + 0x01);
 
-       allocate_device_space(pd, 0x0, 0x100, &port, &memaddr);
+       PCI_SET_DATA(0x10, memaddr);
+
+//     allocate_device_space(pd, 0x0, 0x100, &port, &memaddr);
 
        snprintf(tmpstr, sizeof(tmpstr), "faa addr=0x%llx "
            "pci_little_endian=1", (long long)memaddr);