Re: xxxVERBOSE module?

[Paul Goyette <paul%whooppee.com@localhost>]

On Sat, 22 May 2010, John Nemeth wrote:

> } (referring to loading the pciverbose module...)
> } I guess I can probably remove those changes.  So we'll have to rely on
>
>     Although, you can't test them, possibly keep them.  We do want to
> support hotswap PCI at some point.

It turns out that I need to keep them after all!  Without an explicit 
load, the modules don't get initalized until much later in system 
startup, and this module beomces rather useless.  :)

There is still one problem, though.  As you (John) pointed out earlier, 
we don't have any accessible filesystems from which to load modules. 
But unfortunately, the kern_module subsystem doesn't seem to realize 
this.  So, if the pci code requests the module to be loaded, and the 
module is neither built-in nor provided by the boot loader, it _will_ 
attempt to load from the filesystem.  I expected it to fail, but the 
failure mode is rather ungraceful - the kernel panics with backtrace

        _atomic_inc_32
        namei + x109
        vn_open + x84
        kobj_load_vfs + x82
        module_load_vfs + x2cf
        module_do_load + 3e9
        module_load + x68

It would seem to me that somewhere in this mess we should simply return 
ENOENT (or some other appropriate errno).

> Also, dyoung@ is in the process of
> merging cardbus into PCI.  I don't know if your changes would cause
> mod_verbose to be autoloaded for cardbus, which uses PCIVERBOSE, but
> cardbus insertion should be handled at some point.  And, of course,
> there is PCIe and expresscard on the horizon.  expresscard is basically
> hotswap PCIe along with USB (i.e.  an expresscard slot brings out
> signals for both and the card determines which one it is going to
> use).

Both of these will be reasonable.  I've already updated all the cardbus 
references to the pci_find{vendor,product} routines, so it would be a 
simple matter of making the pciverbose module gets (re)loaded.

>     What about X?  What does it use for scanning the PCI bus?

I suspect it uses libpci - I'll be doing a full-tree search for libpci 
shortly.


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