Re: Add a "enable" sysfs attribute to the pci devices to allow userspace (Xorg) to enable devices without doing foul direct access

[Krzysztof Halasa <khc@pm.waw.pl>]

Kyle Moffett <mrmacman_g4@mac.com> writes:

> This is *exactly* what we don't want to do!  The whole point of this
> thread is to prevent the need to use /dev/mem and /dev/kmem for
> anything except debugging.

Look, it's me who's using that and I tell you I want just that :-)

> Ewww, I certainly wouldn't trust a binary statically-linked binary
> program that mmaps /dev/mem or /dev/kmem

And would you trust a binary which doesn't have "/dev/mem" string
in it?

Anyway you can compile it yourself if you want. It's not about trust,
it's about simplicity and robustness.

>    #! /bin/sh
>    cp firmware.bin /lib/firmware/some_firmware_file.bin
>    echo -n eeprom_load_driver >/sys/device/$PCI_ID/bind
>    echo -n 1 >/sys/device/$PCI_ID/unbind
>
> Simple, obviously correct, and uses a nice reuseable driver too!

Sure. If the driver is loaded/available. What if, say, the
distribution you use doesn't have it?

> No!  That would be even worse!  You're then having userspace poke at
> the driver while a kernel driver is loaded, which is *exactly* what X
> is getting into trouble for doing.

So what? The driver and EEPROM updater don't conflict.

>  If you want to add firmware
> update capability, add it to the preexisting primary driver.

It will not load with blank or invalid EEPROM :-)

> No, not an "enable" interface.  In this case the kernel should do
> basically all of the poking at PCI resources for you.

Because?

>  If you
> _really_ want to do that kind of update in userspace, write a stub
> driver which just enables the device on bind, disables it on unbind,
> and mmap and write to the sysfs "rom" file.

It has nothing to do with any "ROM".
-- 
Krzysztof Halasa
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