linux-kernel - Re: [PATCH v2] platform/x86/intel/ifs: Allow non-default names for IFS image

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Date:   Sun, 10 Jul 2022 09:43:24 -0700
From:   "Joseph, Jithu" <jithu.joseph@...el.com>
To:     Hans de Goede <hdegoede@...hat.com>, <markgross@...nel.org>
CC:     <ashok.raj@...el.com>, <tony.luck@...el.com>,
        <gregkh@...uxfoundation.org>, <ravi.v.shankar@...el.com>,
        <linux-kernel@...r.kernel.org>,
        <platform-driver-x86@...r.kernel.org>, <patches@...ts.linux.dev>
Subject: Re: [PATCH v2] platform/x86/intel/ifs: Allow non-default names for
 IFS image



On 7/10/2022 9:12 AM, Hans de Goede wrote:
> Hi,
> 
> On 7/10/22 18:00, Jithu Joseph wrote:
>> 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.
>>
>> Modify the semantics of the driver file
>> /sys/devices/virtual/misc/intel_ifs_0/reload such that,
>> it interprets the input as the filename to be loaded.
> 
> Much better, but I do wonder about the behavior of still loading
> the default filename at module-init?   If there can be multiple
> different "test-patterns" then does it not make more sense to
> let the user always load the desired pattern before testing first?

The default image provides bulk of the test coverage and the additional ones
provide marginal additional test coverage. That is why, we still kept
loading it by default

> 
> Not doing the initial load at module-load time will also speed-up
> the module initialization and thus booting the system. Especially
> on many-core servers this might make a measurable difference
> in module-init time.

Thanks for these inputs Hans, I do see your concern. Let me take these
concerns to internal folks, before I get back on this.

Jithu