DDE Linux26 in the Hurd

Björn Döbel doebel at os.inf.tu-dresden.de
Thu Jan 28 14:39:21 CET 2010


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Hi,

> You missed my point. I understand that each driver runs in a separate program.
> The problem is that a device has to find the bus where it is located. In the
> current implementation, a driver can only scan 32 devices. If we have 33 devices
> in the system, its driver thinks there isn't such a device and fails to work.
> 
> So I suggest why not let the logical bus contains all devices in the system.

Because in a secure system you don't want the NIC device driver to see
all other devices. This is why we need an IO manager that manages access
to devices on a per-driver basis.

> Thus, the driver can always find its device no matter where the device is
> located, and we don't need an IO manager to pre-configure the logical PCI bus as
> Bjoern said, which seems quite complex.
> 
> By the way, does DDEKit treat a device with 2 functions as two logical devices
> or just one? The `func` of `ddekit_pci_dev` is always 0 and
> `ddekit_pci_find_device_fixed` only uses the argument `slot`. Either DDEKit
> treat a device with multiple functions as several logical devices or only one
> function in a device is exposed to DDE Linux26. Both seems not very reasonable.

Most probably we never stumbled over a multi-function device so far, so
I'd consider this a bug rather than a reasonable decision. ;)

Bjoern
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