Re: [gentoo-releng] Automating the process of building kernel pci drivers

[Daniel Drake <dsd@gentoo.org>]

Chris White wrote:
>     Here's a proposal I had after talking over with some kernel devs and
> plasmaroo (since he works on genkernel):

Kernel hackers have been thinking about this for eternities but have never
come up with a perfect solution.

Here's one problem I can see:

http://sosdg.org/~coywolf/lxr/source/drivers/ide/pci/amd74xx.c#L504

You can see in that table, that support for certain devices depends on the
CONFIG_BLK_DEV_IDE_SATA option. When you do your first-pass, presumably using
a config where every PCI-related option is selected, you'll get the amd74xx
driver providing support for those devices. Your script needs to be able to
detect that support for that particular device is *also* dependant on that
option, otherwise it wouldn't be selected when the users build.
[ This is ignoring the fact that there's another driver for this hardware in
the kernel. I'm sure there are other drivers which genuinely depend on certain
other config options for device support ]

Which brings up the next question, once the utility has figured out that I
need modules including snd-intel8x0, amd74xx, forcedeth, how is it going to
then deduce that the options required are CONFIG_SND_INTEL8X0,
CONFIG_BLK_DEV_AMD74XX and CONFIG_FORCEDETH?

Also, the clashing problem.. Drivers such as 8139cp and 8139too support the
same PCI devices, but you can't figure out which driver is useful until you
probe the hardware. It's usually safe to build both. But when you come to
other situations, such as sk98lin vs skge (almost identical device tables),
you are only ever going to want one or the other.

Daniel
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