linux-kernel - Re: [PATCH 01/15] taint: add module firmware crash taint support

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Message-ID: <20200509164653.GK11244@42.do-not-panic.com>
Date:   Sat, 9 May 2020 16:46:53 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Rafael Aquini <aquini@...hat.com>
Cc:     jeyu@...nel.org, akpm@...ux-foundation.org, arnd@...db.de,
        rostedt@...dmis.org, mingo@...hat.com, cai@....pw,
        dyoung@...hat.com, bhe@...hat.com, peterz@...radead.org,
        tglx@...utronix.de, gpiccoli@...onical.com, pmladek@...e.com,
        tiwai@...e.de, schlad@...e.de, andriy.shevchenko@...ux.intel.com,
        keescook@...omium.org, daniel.vetter@...ll.ch, will@...nel.org,
        mchehab+samsung@...nel.org, kvalo@...eaurora.org,
        davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 01/15] taint: add module firmware crash taint support

On Sat, May 09, 2020 at 11:18:29AM -0400, Rafael Aquini wrote:
> We are still missing the documentation bits for this
> new flag, though.

Ah yeah sorry about that.

> How about having a blurb similar to:
> 
> diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
> index 71e9184a9079..5c6a9e2478b0 100644
> --- a/Documentation/admin-guide/tainted-kernels.rst
> +++ b/Documentation/admin-guide/tainted-kernels.rst
> @@ -100,6 +100,7 @@ Bit  Log  Number  Reason that got the kernel tainted
>   15  _/K   32768  kernel has been live patched
>   16  _/X   65536  auxiliary taint, defined for and used by distros
>   17  _/T  131072  kernel was built with the struct randomization plugin
> + 18  _/Q  262144  driver firmware crash annotation
>  ===  ===  ======  ========================================================
> 
>  Note: The character ``_`` is representing a blank in this table to make reading
> @@ -162,3 +163,7 @@ More detailed explanation for tainting
>       produce extremely unusual kernel structure layouts (even performance
>       pathological ones), which is important to know when debugging. Set at
>       build time.
> +
> + 18) ``Q`` Device drivers might annotate the kernel with this taint, in cases
> +     their firmware might have crashed leaving the driver in a crippled and
> +     potentially useless state.

Sure, I'll modify it a bit to add the use case to help with support
issues, ie, to help rule out firmware issues.

I'm starting to think that to make this even more usesul later we may
want to add a uevent to add_taint() so that userspace can decide to look
into this, ignore it, or report something to the user, say on their
desktop.

  Luis