cvs commit: src/sys/conf files src/sys/dev/uart uart_cpu.h uart_cpu_alpha.c uart_cpu_amd64.c uart_cpu_i386.c uart_cpu_ia64.c uart_cpu_pc98.c uart_cpu_sparc64.c uart_subr.c

Valentin Nechayev netch at ivb.nn.kiev.ua
Sun Mar 21 01:54:21 PST 2004


 Sat, Mar 20, 2004 at 12:04:37, marcel (Marcel Moolenaar) wrote:

>> Only for devices that have fixed addresses.  This wouldn't be true for
>> devices on the PCI bus, where probe order could affect the resources
>> assigned to a given device.  The only real way for self-enumearting
>> busses are a bus-specific address.
MM> Devices that don't have a fixed address cannot be used as low-level
MM> console as there's no way we can know where the device is.

Fixed address does not obligate to be fixed port address.
E.g., PCI bus address can uniquely identify extension card and single
device on it. For ethernet cards, MAC address is unique identifier, so
identification is based on feature, not port address or even bus address.
It is useful even for low-level console: there is no unavoidable limitation
not to reconfigure console (or even add additional consoles).

Thus happened that hints are used not only as attaching address helpers,
but also as enumeration helpers. It is highly important task for many
situations to wire down enumeration. Old config style with 'device xx1 at
yy0 target 3...' does this. If one say hints can't satisfy this task (there
was such voices in this thread), I treat them as useless and
highly confusing mechanism.


-netch-


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