linux-kernel - Re: [PATCH v2 12/14] platform/x86/intel/ifs: Add current

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Message-ID: <Y3Ei7Nc+1wGOF6fk@a4bf019067fa.jf.intel.com>
Date:   Sun, 13 Nov 2022 09:01:32 -0800
From:   Ashok Raj <ashok.raj@...el.com>
To:     Borislav Petkov <bp@...en8.de>
CC:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        Thiago Macieira <thiago.macieira@...el.com>,
        "Luck, Tony" <tony.luck@...el.com>,
        "Joseph, Jithu" <jithu.joseph@...el.com>,
        "hdegoede@...hat.com" <hdegoede@...hat.com>,
        "markgross@...nel.org" <markgross@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "x86@...nel.org" <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        "patches@...ts.linux.dev" <patches@...ts.linux.dev>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Jimenez Gonzalez, Athenas" <athenas.jimenez.gonzalez@...el.com>,
        "Mehta, Sohil" <sohil.mehta@...el.com>,
        Ashok Raj <ashok.raj@...el.com>
Subject: Re: [PATCH v2 12/14] platform/x86/intel/ifs: Add current_batch sysfs
 entry

On Sun, Nov 13, 2022 at 04:58:52PM +0100, Borislav Petkov wrote:
> On Sun, Nov 13, 2022 at 07:15:03AM -0800, Ashok Raj wrote:
> > Do you expect the /lib/firmware/intel/ifs_0/ to contain *ONLY* files for
> > this platform? For microcode we have everything in the public release
> > included here.
> 
> Same as microcode, as I said further down in my mail:
> 
> "And, ofcourse it would check the format of that string against family,
-----------------^^ It is user space or the kernel driver?

> model, stepping and sequence number (btw this way you drop your
> limitation of 256 for the sequence number which you don't really need
> either)."
> 
> > In the above proposal, you can *ONLY* put files for this platform
> > unlike simply copying everything released and let the kernel pick the
> > right one since it does the ff-mm-ss-*.scan lookup. Only the batch
> > number is supplied from user space.
> 
> No, see above. You check the filename against the current f/m/s. Just
> like microcode.

If it's Ok to ask a question. "You" above is the kernel?

Microcode has no such functionality today right? User space 
never inputs a filename, only performs echo 1 > reload.

If a file name composed by the kernel exists, then it checks the header
validity before proceeding.

Apologize if I misunderstood you.

> 
> > Even in the current implementation, user doesn't need to know f/m/s.
> > That's something the driver selects automatically, just like what
> > microcode does for reload.
> 
> Basically what I'm saying all this time.
> 
> > Isn't it simple now? No need to check if user supplied the right f/m/s
> > since its not a user input, kernel composes that automatically.
> 
> Let's see
> 
> * try echoing a magic number into some sysfs file
> 
> vs
> 
> * simply try *all* files in a directory
> 
> Latter is even simpler because you don't have to explain anything about
> sequence numbers - the user doesn't need to know.

Ok, so can you take through how that is going to work.. 

for i in *
do
	echo $i > batch
done

If some of the files are for a different fms, kernel will check the format
and ignores the input.

So some of the files will work, some will fail, and user space doesn't
care? 

Please pardon if I misunderstood you.

> Ashok, you prove for the nth time that you don't really read my emails.
> Sorry, try again.

I absolutely read your emails Boris. But when I have a misunderstanding its
an iterative process. 

Asking a question or responding to your email doesn't mean I'm willfully
ignoring, or have a ill/malice intend. 

You are reviewing the code and I'm simply discussing what each person
means. I hope its OK to have a dialog.

Cheers,
Ashok