linux-kernel - Re: Dell Inc. XPS 13 9343/0TM99H fails to boot v4.16-rc5

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Date:   Tue, 13 Mar 2018 06:51:09 +0100
From:   Dominik Brodowski <linux@...inikbrodowski.net>
To:     Mario.Limonciello@...l.com
Cc:     dvhart@...radead.org, platform-driver-x86@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: Dell Inc. XPS 13 9343/0TM99H fails to boot v4.16-rc5

On Mon, Mar 12, 2018 at 10:42:01PM +0000, Mario.Limonciello@...l.com wrote:
> 
> 
> > -----Original Message-----
> > From: Dominik Brodowski [mailto:linux@...inikbrodowski.net]
> > Sent: Tuesday, March 13, 2018 2:54 AM
> > To: dvhart@...radead.org; Limonciello, Mario <Mario_Limonciello@...l.com>
> > Cc: platform-driver-x86@...r.kernel.org; linux-kernel@...r.kernel.org
> > Subject: Dell Inc. XPS 13 9343/0TM99H fails to boot v4.16-rc5
> > 
> > Mario,
> > 
> > unfortunately, my Dell Inc. XPS 13 9343/0TM99H, BIOS A11 12/08/2016 fails to
> > boot v4.16-rc5. More exactly, I could bisect it down to commit 25d47027e10
> > ("platform/x86: dell-smbios: Link all dell-smbios-* modules together").
> > Usually, I have enabled
> > 
> > CONFIG_SENSORS_DELL_SMM=y
> > CONFIG_DELL_SMBIOS=y
> > CONFIG_DELL_SMBIOS_WMI=y
> > CONFIG_DELL_SMBIOS_SMM=y
> > CONFIG_DELL_LAPTOP=y
> > CONFIG_DELL_WMI=y
> > CONFIG_DELL_WMI_DESCRIPTOR=y
> > # CONFIG_DELL_WMI_AIO is not set
> > # CONFIG_DELL_WMI_LED is not set
> > # CONFIG_DELL_SMO8800 is not set
> > # CONFIG_DELL_RBTN is not set
> > # CONFIG_DELL_RBU is not set
> > 
> > For v4.16-rc5 to work, I need to manually disable DELL_SMBIOS_WMI:
> > 
> > -CONFIG_DELL_SMBIOS_WMI=y
> > +# CONFIG_DELL_SMBIOS_WMI is not set
> > 
> > Any ideas?
> > 
> Dominick,
> 
> Interesting.  Can you please change CONFIG_DELL_SMBIOS to a module
> and see if that behavior persists?  If it does, can you please blacklist it on
> the kernel command line and try to load it manually and share any
> backtrace?

Mario,

building and running it as a *module* works flawlessly. But that was
actually expected after a 'grep "initcall"' in drivers/platform/x86:

As Darren pointed out, DELL_SMBIOS_WMI depends on ACPI_WMI, so probably
ACPI_WMI needs to be initialized first. However, the all-in-one
dell-smbios.o is run as subsys_initcall(), same as wmi.o
(subsys_initcall_sync() there).

If both are built-ins, that means that dell-smbios.o is run first, and wmi.o
second. Changing dell-smbios.o to run at the later fs_initcall() level
instead lets me boot the kernel. HOWEVER:

1) Is there a reason why both the core and the dell-smbios-smm driver have
   to run already at subsys_initcall() time? They did so previous to your
   patch. Is it OK to defer these parts opf the all-in-one dell-smbios.o
   to fs_initcall(), or even to the default device_initcall()?

2) dell-smbios-wmi depends on (well, selects) DELL_WMI_DESCRIPTOR. The
   dell-smbios-wmi is running at the default device_initcall() time, but
   (AFAICS) probably later than the initialization of dell-smbios-wmi.o.
   May I presume that this poses no additional problem?

Thanks,
	Dominik