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Date:   Thu, 28 Jul 2022 09:57:16 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     kah.jing.lee@intel.com
Cc:     linux-kernel@vger.kernel.org, arnd@arndb.de,
        rafael.j.wysocki@intel.com, tien.sung.ang@intel.com,
        dinh.nguyen@intel.com, Zhou@kroah.com,
        Furong <furong.zhou@intel.com>,
        Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Subject: Re: [PATCH v2 1/3] drivers: misc: intel_sysid: Add sysid from arch
 to drivers
Message-ID: <YuJBXLtLYywGsXDu@kroah.com>
References: <20220721123017.416438-1-kah.jing.lee@intel.com>
 <20220721123149.416618-1-kah.jing.lee@intel.com>
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On Thu, Jul 21, 2022 at 08:31:50PM +0800, kah.jing.lee@intel.com wrote:
> From: Kah Jing Lee <kah.jing.lee@intel.com>
> 
> Add new sysid driver. The Altera(Intel) Sysid component is generally part
> of an FPGA design. The component can be hotplugged when the FPGA is
> reconfigured. This driver support the component being hotplugged.
> The sysid driver stores unique 32-bit id value which is similar to a
> check-sum value; different components, different configuration options,
> or both, can be configured to produce different id values. Timestamp field
> is the unique 32-bit value that is based on the system generation time.

I really do not understand what this driver does at all, sorry.  It only
exports 2 sysfs files.  Who will use those sysfs files?  What are they
for?  Why is a driver needed at all as all you are doing is reading 2
memory values from the device, right?  Why is the kernel responsible for
doing the data conversion logic and not userspace?

> There are two basic ways to use the system ID core:
> - Verify the system ID before downloading new software to a system. This
> method can be used by software development tools, before downloading a
> program to a target hardware system, if the program is compiled for
> different hardware.

verify it how?  This is just a random value that we have no idea how to
treat it.

> - Check system ID after reset. If a program is running on hardware other
> than the expected Platform Designer system, the program may fail to
> function altogether. If the program does not crash, it can behave
> erroneously in subtle ways that are difficult to debug. To protect against
> this case, a program can compare the expected system ID against the system
> ID core, and report an error if they do not match.

Where are these ids listed to be able to verify anything?

What userspace tools use this new driver?

thanks,

greg k-h