Xen-Devel Archive on lore.kernel.org
 help / color / Atom feed
From: Jan Beulich <jbeulich@suse.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Xen-devel <xen-devel@lists.xenproject.org>,
	"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH 3/2] x86/desc: Drop __HYPERVISOR_CS32
Date: Fri, 9 Aug 2019 17:52:45 +0200
Message-ID: <2aed27f4-4af2-7e5f-c075-3e4d66dd44e9@suse.com> (raw)
In-Reply-To: <eb6e00a0-2937-953e-a57b-c46ab45dfd5a@citrix.com>

On 09.08.2019 17:36, Andrew Cooper wrote:
> On 09/08/2019 13:50, Jan Beulich wrote:
>> On 09.08.2019 14:39, Andrew Cooper wrote:
>>> Xen, being 64bit only these days, has no use for a 32bit Ring 0 code
>>> segment.
>>> Delete __HYPERVISOR_CS32 and remove it from the GDTs.  Also delete
>>> __HYPERVISOR_CS64 and use __HYPERVISOR_CS uniformly.
>> Long, long ago we've been considering doing this. Agreed,
>> nothing has surfaced to actually use it, but I wouldn't
>> subscribe to "has no use": We will need it if we ever want
>> to be able to run on 32-bit EFI _and_ invoke runtime
>> services there. Back then through the consideration against
>> dropping it was that we may want to invoke 32-bit BIOS
>> services (PCI, VGA) from the hypervisor.
> I hadn't realised these had even been considered in the past.  I don't
> think either of these are likely to happen now.
> As for the text, Xen really does have no users of a 32bit R0 code
> segment, and the statement does not preclude the fact that there may be
> legitimate uses for CS32.
> Would you be happier with "days, and does not use a 32bit Ring 0 code
> segment." ?

Yes, "does not use" is definitely more correct imo, as would be
"has no user" (note the extra "r" compared to your original text;
your reply makes me wonder whether it was simply a typo).


Xen-devel mailing list

      reply index

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 10:34 [Xen-devel] [PATCH v2 0/2] x86/boot: cleanup Jan Beulich
2019-08-09 10:38 ` [Xen-devel] [PATCH v2 1/2] x86: define a few selector values Jan Beulich
2019-08-09 11:50   ` Andrew Cooper
2019-08-09 12:35     ` Jan Beulich
2019-08-23  2:38   ` Tian, Kevin
2019-08-09 10:40 ` [Xen-devel] [PATCH v2 2/2] x86/desc: Build boot_{, compat_}gdt[] in C Jan Beulich
2019-08-09 12:19   ` Andrew Cooper
2019-08-09 12:43     ` Jan Beulich
2019-08-09 13:07       ` Andrew Cooper
2019-08-09 13:18         ` Jan Beulich
2019-08-09 15:25           ` Andrew Cooper
2019-08-12  7:32   ` Jan Beulich
2019-08-12 10:36     ` Andrew Cooper
2019-08-09 10:41 ` [Xen-devel] [PATCH v2 0/2] x86/boot: cleanup Jan Beulich
2019-08-09 12:39 ` [Xen-devel] [PATCH 3/2] x86/desc: Drop __HYPERVISOR_CS32 Andrew Cooper
2019-08-09 12:50   ` Jan Beulich
2019-08-09 15:36     ` Andrew Cooper
2019-08-09 15:52       ` Jan Beulich [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 \
    --in-reply-to=2aed27f4-4af2-7e5f-c075-3e4d66dd44e9@suse.com \
    --to=jbeulich@suse.com \
    --cc=andrew.cooper3@citrix.com \
    --cc=roger.pau@citrix.com \
    --cc=wl@xen.org \
    --cc=xen-devel@lists.xenproject.org \


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

Xen-Devel Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/xen-devel/0 xen-devel/git/0.git
	git clone --mirror https://lore.kernel.org/xen-devel/1 xen-devel/git/1.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 xen-devel xen-devel/ https://lore.kernel.org/xen-devel \
		xen-devel@lists.xenproject.org xen-devel@lists.xen.org
	public-inbox-index xen-devel

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone https://public-inbox.org/public-inbox.git