linux-kernel - Re: [PATCH v4 07/12] efi: passing kexec necessary efi data via setup

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Message-ID: <20131203015613.GB3980@dhcp-16-126.nay.redhat.com>
Date:	Tue, 3 Dec 2013 09:56:13 +0800
From:	Dave Young <dyoung@...hat.com>
To:	Toshi Kani <toshi.kani@...com>
Cc:	Borislav Petkov <bp@...en8.de>, linux-kernel@...r.kernel.org,
	linux-efi@...r.kernel.org, x86@...nel.org, mjg59@...f.ucam.org,
	hpa@...or.com, James.Bottomley@...senPartnership.com,
	vgoyal@...hat.com, ebiederm@...ssion.com, horms@...ge.net.au,
	kexec@...ts.infradead.org, greg@...ah.com, matt@...sole-pimps.org
Subject: Re: [PATCH v4 07/12] efi: passing kexec necessary efi data via
 setup_data

On 12/02/13 at 06:31pm, Toshi Kani wrote:
> On Mon, 2013-12-02 at 15:33 -0700, Toshi Kani wrote:
> > On Fri, 2013-11-29 at 17:14 +0800, Dave Young wrote:
> > > On 11/27/13 at 03:07pm, Borislav Petkov wrote:
> > > > On Tue, Nov 26, 2013 at 01:57:52PM +0800, Dave Young wrote:
> > > > > Add a new setup_data type SETUP_EFI for kexec use.
> > > > > Passing the saved fw_vendor, runtime, config tables and
> > > > > efi runtime mappings.
> > > > > 
> > > > > When entering virtual mode, directly mapping the efi
> > > > > runtime ragions which we passed in previously. And skip
> > > > > the step to call SetVirtualAddressMap.
> > > > > 
> > > > > Specially for HP z420 workstation it need another variable
> > > > > saving,
> > > > 
> > > > Why the special handling? Does that mean, this is going to be the case
> > > > for other HP UEFI implementations too?
> > > 
> > > I have only one HP machine for testing, Maybe Toshi can help to verify
> > > on other machines. Just comment out the function efi_reuse_config to see
> > > if kexec kernel panic.
> > 
> > My system (HP prototype server) did not need the special handling in
> > efi_reuse_config().  I will check with firmware team to get more
> > information on this.
> 
> I have one question.  I think this special handling assumes that
> efi.smbios contains a virtual address on HP z420.  So, how does the 1st
> kernel set a virtual address to efi.smbios in the first place?

Hi, Toshi,

It's originally a physical address, I think kernel does not change it.
As the fw_vendor, runtime etc. are changed to virt addr by firmware, so I
assume smbios on Hp z420 is also changed by firmware after becoming virtual mode.

Thanks
Dave
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