linux-kernel - Re: RFC: WMI Enhancements

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Date:   Tue, 9 May 2017 21:19:52 +0200
From:   Pali Rohár <pali.rohar@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     Mario Limonciello <Mario.Limonciello@...l.com>,
        "dvhart@...radead.org" <dvhart@...radead.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Andy Lutomirski <luto@...capital.net>,
        "Brown, Len" <len.brown@...el.com>,
        Corentin Chary <corentin.chary@...il.com>,
        Andy Lutomirski <luto@...nel.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Platform Driver <platform-driver-x86@...r.kernel.org>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>
Subject: Re: RFC: WMI Enhancements

On Tuesday 09 May 2017 21:04:15 Andy Shevchenko wrote:
> On Tue, May 9, 2017 at 9:10 PM,  <Mario.Limonciello@...l.com> wrote:
> >> > > Then took relevant decompression code and it really
> >> > > decompressed that binary MOF WMI buffer. But still
> >> > > decompressed format is binary, but I now see all WMI GUID
> >> > > encoded in UTF-16. Decompressed BMF file has again "FOMB"
> >> > > magic header.
> >> > 
> >> > Well that's great.  Is it possible that this compression is used
> >> > for every time a class was declared?
> >> 
> >> Looks like not. That decompressed output seems to be not
> >> compressed anymore. Just use same magic header.
> > 
> > Actually it looks like a new magic header to me after decompressed.
> > 
> > 46 4f 4d 42 54 15 00 00  01 00 00 00 01 00 00 00
> > That's now FOMBT
> 
> I think you just mistakenly take 0x54 as letter when it looks more
> like
> 
> 0x00001554
> 0x00000001
> 0x00000001
> 
> from the above dump.

I looked at more decompressed BMF dumps from ACPI WMI and they have 
different 5th and 6th bytes. So they are really not FOMBT.

46 4f 4d 42 26 35 00 00 01 00 00 00 01 00 00 00
46 4f 4d 42 fa 17 00 00 01 00 00 00 01 00 00 00
46 4f 4d 42 8e 11 00 00 01 00 00 00 01 00 00 00
46 4f 4d 42 ac 1b 00 00 01 00 00 00 01 00 00 00

So magic is only FOMB.

-- 
Pali Rohár
pali.rohar@...il.com

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