Re: [Qemu-devel] [PATCH] Make rtl8139 network interface card compatible with Mac OS 10.4

[Programmingkid]

On Jan 2, 2016, at 4:39 AM, Mark Cave-Ayland wrote:

> On 02/01/16 04:00, Programmingkid wrote:
> 
>>> Well they are returning non-zero values, so that's good. After a bit
>>> more poking, something doesn't make sense - in that same file
>>> RTL8139::initPCIConfigSpace() claims to set the bus master bit, but if I
>>> add tracing to hw/pci/pci-host.c then I don't see any writes to the PCI
>>> command register outside of OpenBIOS? Any chance you can add debugging
>>> to the before and after values for the reg16 variable which this
>>> function claims to set?
>>> 
>>> Also with similar tracing involved, apparently the writes to PCI I/O
>>> space in order to access the chip registers are actually going through
>>> pci_host_config_write(), i.e. configuration space rather than I/O space
>>> which is why they aren't accessing the chip registers. So more digging
>>> is required to figure out why this is happening.
>>> 
>> 
>> I added code to the initPCIConfigSpace() function that prints every register 
>> from 0 to 0x3e. All of the registers returned zero. My patch was fully 
>> applied when the driver printed all these values. I even had all the 
>> registers set to 0x99 then printed all the registers again. The registers 
>> all returned zero again. The driver was able to obtain the correct device, 
>> function, and bus numbers. PCI configuration space is not being accessed 
>> correctly by this driver. 
> 
> After some head scratching chasing this through for several hours
> yesterday, I've worked out what is happening and have a patchset for
> OpenBIOS which should fix the issue (will post later along with some
> other PCI fixes for testing).
> 
> This is actually a bug in Darwin in that it doesn't parse the address
> space part of the "ranges" property for the /pci node. OpenBIOS adds all
> 3 spaces to the "ranges" - configuration, I/O and memory compared to
> real Macs which only add I/O and memory. Which is generally fine because
> each entry contains a 2-bit indicator so that the OS knows which entry
> represents each address space.
> 
> Except that Darwin evidently doesn't bother parsing the address space
> from each "range" entry and blindly assumes that entry 0 is I/O space
> and entry 1 is memory space as would be found in a real Mac device tree.
> The result of this is that currently I/O accesses go to entry 0 (config
> space) and memory accesses go to entry 1 (I/O space) which is why the
> RTL8139 happens to work with your patch to force bus mastering.
> 
> AFAICT with basic testing here, forcing the /pci node to mimic that of a
> real Mac by omitting the configuration space entry seems to fix all PCI
> accesses (or at least they get routed to the correct address spaces), I
> see an attempt to set the bus master bit in the command register, and I
> don't get a reset timeout on startup for the RTL8139 anymore.


Wow, you figure out stuff fast! Will be waiting for your patches.