[Qemu-devel] ISA device and shared memory

[Albin Kauffmann]

Hello,

I'm trying to add the support for an old com90c65 ISA card (a network 
device using the old ARCnet protocol and handled by the com90xx Linux 
module). This device is using both IO ports and IO memory.

The I/O ports are working and the code is largely inspired from the 
ne2k_isa support. However, I have not find the right way to register the 
I/O memory. I've tried the following code :


static const MemoryRegionOps com90c65_mmio_ops = {
    .read = com90c65_mmio_read,
    .write = com90c65_mmio_write,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

[...]

memory_region_init_io(&s->mmio, &com90c65_mmio_ops, s, "com90c65-mmio",
                      size);
memory_region_add_subregion(isa_address_space(dev),
                            isa_mem_base + isa->mmiobase, &s->mmio);


Depending on mmiobase, I get :
 - mmiobase == 0xd0000 : no error message but debuging QEMU shows me 
that my read/write functions are not called.
 - mmiobase == 0xd0800 : the following error :
qemu-system-i386: [...]/qemu-1.1.0/exec.c:2371: register_subpage: 
Assertion `existing->mr->subpage || existing->mr == &io_mem_unassigned' 
failed

Because the ISA and PCI memory areas seem to overlap and as the ISA bus 
is accessed via a PCI to ISA bridge, they might be something else to 
initialize but I can't find what and browsing the QEMU code didn't help me.

However, I have managed to make it work by using a call to 
memory_region_add_subregion_overlap() with a priority bigger than the 
PCI one (priority >= 2) but it only works with mmiobase == 0xd0000.

As it might also be a seabios configuration problem, I have added the 
seabios mailing list in the recipients.

In attachement, you'll find the output of info mtree, info qtree and the 
logs of seabios.

Any help will be really appreciated,
Thanks :)

--
Albin Kauffmann

seabios.log
Description: Text document

info-mtree.txt
Description: Text document

info-qtree.txt
Description: Text document