LKML Archive on
 help / color / Atom feed
From: Jeremy Fitzhardinge <>
To: "H. Peter Anvin" <>
Cc: Linux Kernel Mailing List <>,
	Ingo Molnar <>, Thomas Gleixner <>,
	"Pan, Jacob jun" <>,
	Rusty Russell <>,
	Andres Salomon <>
Subject: Re: RFC: can we kill the KEEP_SEGMENTS bzImage flag?
Date: Thu, 03 Feb 2011 12:01:00 -0800
Message-ID: <> (raw)
In-Reply-To: <>

On 02/03/2011 09:19 AM, H. Peter Anvin wrote:
>>   Bit 6 (write): KEEP_SEGMENTS
>>         Protocol: 2.07+
>>         - If 0, reload the segment registers in the 32bit entry point.
>>         - If 1, do not reload the segment registers in the 32bit entry point.
>>                 Assume that %cs %ds %ss %es are all set to flat segments with
>>                 a base of 0 (or the equivalent for their environment).
> Does anything actually rely on this bit or can we kill it?  I think it
> was added as a crutch for paravirtualization, but I'm being told it is
> not used...

We originally added it with the idea that we might change the Xen boot
sequence to just enter via the normal entrypoint before wandering off to
the Xen paravirt path - mostly as a way of making use of the bzImage's
own decompresser rather than having to have that externally.

But we never ended up doing that, so the paravirt boot path is unused by
Xen, and I don't see that changing.

I think VMI may have used it, but that's moot now.

So I think lguest is the only potential user, and I'm not sure if it
actually does.


      reply index

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-03 17:19 H. Peter Anvin
2011-02-03 20:01 ` Jeremy Fitzhardinge [this message]

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \ \ \ \ \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

LKML Archive on

Archives are clonable:
	git clone --mirror lkml/git/0.git
	git clone --mirror lkml/git/1.git
	git clone --mirror lkml/git/2.git
	git clone --mirror lkml/git/3.git
	git clone --mirror lkml/git/4.git
	git clone --mirror lkml/git/5.git
	git clone --mirror lkml/git/6.git
	git clone --mirror lkml/git/7.git
	git clone --mirror lkml/git/8.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 lkml lkml/ \
	public-inbox-index lkml

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone