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Re: [Qemu-devel] [PATCH] Name the default PCI bus "pci.0" on all archite
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] [PATCH] Name the default PCI bus "pci.0" on all architectures |
Date: |
Sat, 29 May 2010 07:13:52 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) |
Paul Brook <address@hidden> writes:
>> The system emulators for each arch are using inconsistent
>> naming for the default PCI bus "pci" vs "pci.0". Since it
>> is conceivable we'll have multiple PCI buses in the future
>> standardize on "pci.0" for all architectures. This ensures
>> mgmt apps can rely on a name when assigning PCI devices an
>> address on the bus using eg '-device e1000,bus=pci.0,addr=3'
>
> No. Bus names are local to the parent device. None of the host bridges
> support multiple bridges, so the ".0" suffix makes no sense. The parent
> device has no idea whether it owns the "default" pci bus or not.
> If you have multiple PCI busses then you can identify them by the device path.
>From qbus_create_inplace():
if (name) {
/* use supplied name */
bus->name = qemu_strdup(name);
} else if (parent && parent->id) {
/* parent device has id -> use it for bus name */
len = strlen(parent->id) + 16;
buf = qemu_malloc(len);
snprintf(buf, len, "%s.%d", parent->id, parent->num_child_bus);
bus->name = buf;
} else {
/* no id -> use lowercase bus type for bus name */
len = strlen(info->name) + 16;
buf = qemu_malloc(len);
len = snprintf(buf, len, "%s.%d", info->name,
parent ? parent->num_child_bus : 0);
for (i = 0; i < len; i++)
buf[i] = qemu_tolower(buf[i]);
bus->name = buf;
}
If appending ".0" really makes no sense when the device has just one
bus, then we shouldn't append it in cases 2 & 3.
But I'd simply append it always. One bus is just as countable as many.