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Subject: Re: [PATCH -mm -v3] x86 boot : export boot_params via sysfs
From: "Huang, Ying" <ying.huang@intel.com>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>, Greg KH <greg@kroah.com>,
       akpm@linux-foundation.org, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>, Andi Kleen <ak@suse.de>,
       linux-kernel@vger.kernel.org
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Date: Tue, 18 Dec 2007 15:29:34 +0800
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On Mon, 2007-12-17 at 21:34 -0700, Eric W. Biederman wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
> 
> > This is directly analogous to how we treat identity information in IDE, or PCI
> > configuration space -- some fields are pre-digested, but the entire raw
> > information is also available.
> 
> Add to that a totally unchanged value can just be easier to get correct.
> 
> Still the kexec code as much as it can should not look there, as we may
> get the same basic information in a couple of different ways.
> 
> EFI memmap vs. e820 for example.  If/when that is the case /sbin/kexec
> should get the information and spit it out into whatever format makes
> sense for the destination kernel.  My sense is just passing through
> values is brittleness where we don't want it.
> 
> However I think being able to get at the raw boot information overall
> sounds useful.  I just don't know if it is generally useful or just
> useful when debugging bootloaders though.

If struct boot_params as a whole is useless for kexec, I can move it to
debugfs, because kexec is the only normal user now. Then which fields of
struct boot_params do you think is useful for kexec?

Refer to include/asm-x86/bootparam.h

edid_info?
e820_entries and e820_map?	maybe useful for kdump
edd related fields (eddbuf, edd_mbr_sig_buffer, etc)? split fields until fundamental types?

Best Regards,
Huang Ying