Re: After upgrading to 4.11.1, wifi driver refuses to load after being unloaded once.

[Luca Coelho <luca@coelho.fi>]

On Wed, 2017-10-18 at 12:50 +0300, Kalle Valo wrote:
> Luca Coelho <luca@coelho.fi> writes:
> 
> > On Wed, 2017-10-18 at 07:59 +0300, Kalle Valo wrote:
> > > Luca Coelho <luca@coelho.fi> writes:
> > > 
> > > > On Tue, 2017-10-17 at 14:23 -0700, Marc MERLIN wrote:
> > > > 
> > > > > I don't know how or why, but I seem to:
> > > > > saruman:~# grep IWLWIFI /boot/config-4.12.10-amd64-preempt-
> > > > > sysrq-
> > > > > 20170406 
> > > > > CONFIG_IWLWIFI=m
> > > > > CONFIG_IWLWIFI_LEDS=y
> > > > > CONFIG_IWLWIFI_OPMODE_MODULAR=y
> > > > > # CONFIG_IWLWIFI_BCAST_FILTERING is not set
> > > > > CONFIG_IWLWIFI_PCIE_RTPM=y
> > > > > CONFIG_IWLWIFI_DEBUG=y
> > > > > CONFIG_IWLWIFI_DEVICE_TRACING=y
> > > > > 
> > > > > I'll remove that, thanks.
> > > > 
> > > > Cool, I think that might help.  If it doesn't, please report a
> > > > bug
> > > > in
> > > > buzilla. ;)
> > > 
> > > But a Kconfig option should never break functionality, so IMHO
> > > this
> > > still sounds like a bug in iwlwifi.
> > 
> > The problem is that to get this to work, some changes need to be
> > made
> > in the platform side.  In this case, the rootport is not configured
> > properly so it won't work.
> 
> Yeah, but users or distros might accidentally enable this Kconfig
> option and break the driver unintentionally. And subtle bugs like
> this
> are even worse as the user will not realise that it's because of a
> new
> Kconfig option.
> 
> So I guess you can't automatically detect it the platform supports
> RTPM,
> right? Maybe there should be a module parameter which has to be set
> to
> enable this? And at least a big fat warning to the user that RTPM is
> enabled, bugs are likely and the user has to know what she's doing.

I thought this was what EXPERT was used for:

menuconfig EXPERT
        bool "Configure standard kernel features (expert users)"
        # Unhide debug options, to make the on-by-default options visible
        select DEBUG_KERNEL
        help
          This option allows certain base kernel options and settings
          to be disabled or tweaked. This is for specialized
          environments which can tolerate a "non-standard" kernel.
          Only use this if you really know what you are doing.


But it seems that it's widely used even by people/distros who don't
know what they are doing. :(

Would it be okay if we just add a printk(KERN_ERR, ...)?


> > We discussed this before and that's why this option now depends on
> > EXPERT.
> 
> Heh, we did? I have no recollection of whatsoever about that :)

I'm not sure you were involved in the discussion, but that discussion
was the reason we introduced EXPERT as a dependency.

--
Luca.