Date: Sat, 14 Sep 2013 14:09:06 -0400 From: Leonardo Passos <lnrdpss@gmail.com> To: freebsd-drivers@freebsd.org Subject: Device hierarchy Message-ID: <CAO10wb6_AoZ9maGhx326tjZ6-aqvyzVV7rBxfOv%2BLOABixs_cw@mail.gmail.com>
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Hi all,
I am checking some code from the FreeBSD repository, and I came across a
situation that I could not explain, at least from the existing
documentation.
Looking at sys/dev/ata/ata-raid.c in the 9.1 release, I see the following
module declaration (line 4616):
static moduledata_t ata_raid_moduledata =
{ "ataraid", ata_raid_module_event_handler, NULL };
DECLARE_MODULE(ata, ata_raid_moduledata, SI_SUB_RAID, SI_ORDER_FIRST);
MODULE_VERSION(ataraid, 1);
MODULE_DEPEND(ataraid, ata, 1, 1, 1);
MODULE_DEPEND(ataraid, ad, 1, 1, 1);
The name of the module, as specified in DECLARE_MODULE, is ata, but the
name provided in the moduledata_t instance is "ataraid". According to the
documentation of DECLARE_MODULE, the name field in the structure instance
(2nd parameter) is the official module name. So, it is correct to assume
that passing "ata" as the first parameter in DECLARE_MODULE is an error, as
it does not match "ataraid", or is it the case that such name is a "don't
care" field, as FreeBSD takes the name as given by the moduledata_t
instance?
Another weird situation appears in sys/dev/ata-isa.c (line 201):
static driver_t ata_isa_driver = {
"ata",
ata_isa_methods,
sizeof(struct ata_channel),
};
DRIVER_MODULE(ata, isa, ata_isa_driver, ata_devclass, 0, 0);
MODULE_DEPEND(ata, ata, 1, 1, 1);
Here, the driver module name is set to "ata", and later, it is stated that
ata depends on ata. Is the dependency referring to another ata module, at a
different level in the driver stacking? How are these names and
dependencies resolved?
Thanks,
Leonardo.
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