Re: -git tree build failure #2: drivers/net/cnic.c:2520: error: implicit declaration of function ‘__symbol_get’

Michael Chan
2009-06-14T02:25:16Z

On Sat, 2009-06-13 at 18:33 -0700, James Bottomley wrote:
> On Sat, 2009-06-13 at 17:43 -0700, Michael Chan wrote:
> > On Sat, 2009-06-13 at 13:42 -0700, James Bottomley wrote:
> > > On Sat, 2009-06-13 at 13:11 -0700, Linus Torvalds wrote:
> > > >
> > > >
> > > > That makes no sense.
> > > >
> > > > Look at the first #include in the file - it already includes
> > > > <linux/module.h>.
> > > >
> > > > Why do we need to do it twice?
> > >
> > > We don't ... it's the wrong fix. The actual problem is that
> > > __symbol_get() is only defined for the modular case. What it looks to
> > > be doing is a reflection call on bnx2_cnic_probe(). I'm not sure why
> > > it's doing this ... other than perhaps cnic wants to avoid an explicit
> > > bnx2 dependency? I actually think it's incorrect, since the netdev code
> > > before it just checked bnx2 is present, so I see no harm in an explicit
> > > call, so this should fix it.
> > >
> > > If it had a good reason for the reflective call, then symbol_get()
> > > without the __ should be used.
> > >
> > > Michael Chan, could you confirm?
> > >
> > Thanks James and Ingo. We don't want to have a symbol dependency on
> > bnx2 because this driver eventually will support the 10G bnx2x driver as
> > well. So we want the driver to support either or both NIC drivers
> > without both drivers loaded. Please use the patch below.
>
> Um, but that's not going to work very well. When you have your 10G
> driver, they'll both have to export the symbol name bnx2_cnic_probe
> which the kernel isn't going to like. You can differentiate the symbols
> and add a multiple symbol lookup in init_bnx2_cnic(), but that's getting
> ugly.

Yeah, the plan is to have a bnx2x_cnic_probe() when we add support for
that. There will be a separate init_bnx2x_cnic() because the hardware
interface is not exactly the same.

>
> What about doing something more standard, like bus matching? That's how
> the SCSI upper layer drivers work: we export a virtual SCSI bus and
> they bind to it if a supporting device appears. You could do something
> similar exporting a virtual cnic bus from your network drivers and get
> the cnic driver to bind to it.
>

This will require some additional infra-structure. We can look into
this when we support the 10G driver. Thanks.