linux-kernel - Re: [PATCH] platform/x86/intel/ifs: Allow non-default names for IFS image

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Date:   Fri, 8 Jul 2022 11:34:40 -0700
From:   "Joseph, Jithu" <jithu.joseph@...el.com>
To:     Greg KH <gregkh@...uxfoundation.org>
CC:     <hdegoede@...hat.com>, <markgross@...nel.org>,
        <ashok.raj@...el.com>, <tony.luck@...el.com>,
        <ravi.v.shankar@...el.com>, <linux-kernel@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <patches@...ts.linux.dev>
Subject: Re: [PATCH] platform/x86/intel/ifs: Allow non-default names for IFS
 image

On 7/8/2022 8:28 AM, Greg KH wrote:
> On Fri, Jul 08, 2022 at 08:19:38AM -0700, Jithu Joseph wrote:
>> Existing implementation limits IFS image to be loaded only from
>> a default file-name (ff-mm-ss.scan).
>>

> 
> Ick, but now what namespace are you saying that path is in?  If you need
> debugging stuff, then put the api/interface in debugfs and use it there,
> don't overload the existing sysfs api to do something different here.

The namespace related confusion could be because, the original commit message
was not using full path-names. The below write-up tries to be more clear on this

Existing implementation limits IFS images to be loaded only from
a default file-name /lib/firmware/intel/ifs/ff-mm-ss.scan.

But there are situations where there may be multiple scan files
that can be run on a particular system stored in /lib/firmware/intel/ifs

E.g.
1. Because test contents are larger than the memory reserved for IFS by BIOS
2. To provide increased test coverage
3. Custom test files to debug certain specific issues in the field

Renaming each of these to ff-mm-ss.scan and then loading might be
possible in some environments. But on systems where /lib is read-only
this is not a practical solution.

Extend the semantics of the driver /sys/devices/virtual/misc/intel_ifs_0/reload
file:

  Writing "1" remains the legacy behavior to load from the default
  ff-mm-ss.scan file.

  Writing some other string is interpreted as a filename in
  /lib/firmware/intel/ifs to be loaded instead of the default file.

> 
>> Fix the below items in adjacent code
>> - Return error when ifs_image_sanity_check() fails in ifs_load_firmware()
>> - Correct documentation "ifs.0"->"ifs"
> 
> That should all be a separate patch, you and Tony know better than this.
> 

Noted ... will send this separately

Jithu