Re: [PATCH v6 2/7] iwlwifi: mei: add the driver to allow cooperation with CSME

Emmanuel Grumbach [off-list ref] writes:

On Mon, Oct 18, 2021 at 1:58 PM Kalle Valo [off-list ref] wrote:

quoted

Emmanuel Grumbach [off-list ref] writes:

quoted

CSME in two words
-----------------
CSME stands for Converged Security and Management Engine. It is
a CPU on the chipset and runs a dedicated firmware.
AMT (Active Management Technology) is one of the applications
that run on that CPU. AMT allows to control the platform remotely.
Here is a partial list of the use cases:
* View the screen of the plaform, with keyboard and mouse (KVM)
* Attach a remote IDE device
* Have a serial console to the device
* Query the state of the platform
* Reset / shut down / boot the platform

[...]

quoted

--- a/drivers/net/wireless/intel/iwlwifi/Kconfig
+++ b/drivers/net/wireless/intel/iwlwifi/Kconfig

@@ -92,6 +92,23 @@ config IWLWIFI_BCAST_FILTERING
        If unsure, don't enable this option, as some programs might
        expect incoming broadcasts for their normal operations.

+config IWLMEI
+     tristate "Intel Management Engine communication over WLAN"
+     depends on INTEL_MEI
+     depends on PM
+     depends on IWLMVM
+     help
+       Enables the iwlmei kernel module. This allows to communicate with
+       the Intel Management Engine over Wifi. This is supported starting
+       from Tiger Lake platforms and has been tested on 9260 devices only.
+       Enabling this option on a platform that has a different device and
+       has Wireless enabled on AMT can prevent WiFi from working correctly.

I don't understand the last sentence, please elaborate. Are you saying
that enabling CONFIG_IWLMEI will break wi-fi in some cases?

Since we don't support all the devices (yet), and we haven't integrated it
with all our devices, then yes, it shouldn't be enabled unless you know
exactly what platform this kernel runs on. 

So if I'm understanding correctly, enabling CONFIG_IWLMEI will break
existing iwlwifi setups? Or am I missing something?

If that's the case when we have a major problem as that would be a
regression. A kconfig option is not a free pass to do all sort of crazy
stuff, and especially it cannot break already working hardware. That
would be considered as a regression and we have a strong rule for
regressions.

This is basically a warning for distros not to enable this kernel
option (just as many others that are specific to a certain use case).
The plan is to add support for more and more devices so that we will
be able to remove this comment and be confident that it can be enabled
on generic platforms as well.

I barely missed the warning and I consider myself as an extra careful
person, I can only imagine how many regular users will enable this
option without thinking twice. And people can use allmodconfig etc as
well.

-- 
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