Re: [patch] x86: Introduce BOOT_EFI and BOOT_CF9 into the reboot sequence loop

From: "H. Peter Anvin" <hpa@zytor.com>
To: "Li, Aubrey" <aubrey.li@linux.intel.com>,
	Matthew Garrett <mjg59@srcf.ucam.org>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
	"alan@linux.intel.com" <alan@linux.intel.com>,
	linux-kernel@vger.kernel.org, Len.Brown@intel.com,
	Adam Williamson <awilliam@redhat.com>
Subject: Re: [patch] x86: Introduce BOOT_EFI and BOOT_CF9 into the reboot sequence loop
Date: Sat, 01 Mar 2014 18:07:18 -0800	[thread overview]
Message-ID: <53129256.6060704@zytor.com> (raw)
In-Reply-To: <53128DA0.9060105@linux.intel.com>

On 03/01/2014 05:47 PM, Li, Aubrey wrote:
> 
> Since we are not able to make things worse, let's make it better. So
> Let's dig into this. For the machine hangs by CF9, it's known to work by
> KBD, right? For the machine hangs by BIOS, do you know which method will
> make reboot work?
> 

No.

> The answer will determine the sequence of the list. If BIOS hangs but
> either of ACPI/KBD/EFI/CF9 works, BIOS is behind of those ways. If BIOS
> hangs, no any other way can make it work. BIOS is still the last way.
> 
> If CF9 hangs while ACPI/KBD hangs as well, and BIOS happened to work(do
> we really have one?), the above list still doesn't make things worse,
> reboot=b and dmidecode table still work.

We obviously have been over this a number of times, and the sad thing is
that we have very limited information.  It is more complex than that,
even... I believe in some cases KBD works but it is slow, and so takes a
while.

	-hpa