From: Jan Beulich <jbeulich@suse.com>
To: David Woodhouse <dwmw2@infradead.org>
Cc: "Andrew Cooper" <andrew.cooper3@citrix.com>,
xen-devel <xen-devel@lists.xenproject.org>,
"Wei Liu" <wl@xen.org>, "Roger Pau Monné" <roger.pau@citrix.com>
Subject: Re: [Xen-devel] [PATCH v2 6/6] x86/boot: Do not use trampoline for no-real-mode boot paths
Date: Tue, 27 Aug 2019 11:07:22 +0200 [thread overview]
Message-ID: <c139b11c-a10a-3e13-ac0a-0ce28f31eef5@suse.com> (raw)
In-Reply-To: <a2143ee639599afb848e168d0f741c5130f7a241.camel@infradead.org>
On 19.08.2019 17:25, David Woodhouse wrote:
> On Mon, 2019-08-12 at 12:55 +0200, Jan Beulich wrote:
>> On 09.08.2019 17:02, David Woodhouse wrote:
>>> @@ -97,7 +100,7 @@ GLOBAL(trampoline_realmode_entry)
>>> cld
>>> cli
>>> lidt trampsym(idt_48)
>>> - lgdt trampsym(gdt_48)
>>> + lgdtl trampsym(gdt_48)
>>
>> Stray / unrelated change (and if needed, then also for lidt)?
>
> The difference between 16bit l.dt and 32-bit l.dtl is that the former
> only loads 24 bits of the actual table address (trampoline_gdt in this
> case).
>
> Thus, when trampoline_gdt is being used in-place, as it is during early
> boot, and *if* the Xen image is loaded higher than 16MiB, lgdt doesn't
> work. That's half a day of my life I want back.
But isn't this an issue even independent of your series? I.e. doesn't
this want to be fixed in a separate (to be backported) patch?
Jan
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next prev parent reply other threads:[~2019-08-27 9:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1565362089.git.dwmw@amazon.co.uk>
2019-08-09 15:01 ` [Xen-devel] [PATCH v2 1/6] x86/boot: Remove gratuitous call back into low-memory code David Woodhouse
2019-08-09 15:01 ` [Xen-devel] [PATCH v2 2/6] x86/boot: Only jump into low trampoline code for real-mode boot David Woodhouse
2019-08-12 9:10 ` Jan Beulich
2019-08-21 14:04 ` David Woodhouse
2019-08-27 8:43 ` Jan Beulich
2019-08-09 15:01 ` [Xen-devel] [PATCH v2 3/6] x86/boot: Split bootsym() into four types of relocations David Woodhouse
2019-08-12 9:41 ` Jan Beulich
2019-08-19 15:24 ` David Woodhouse
2019-08-09 15:02 ` [Xen-devel] [PATCH v2 4/6] x86/boot: Rename trampoline_{start, end} to boot_trampoline_{start, end} David Woodhouse
2019-08-12 9:55 ` Jan Beulich
2019-08-19 15:24 ` David Woodhouse
2019-08-27 8:51 ` Jan Beulich
2019-08-27 9:31 ` David Woodhouse
2019-08-09 15:02 ` [Xen-devel] [PATCH v2 5/6] x86/boot: Copy 16-bit boot variables back up to Xen image David Woodhouse
2019-08-12 10:24 ` Jan Beulich
2019-08-19 15:25 ` David Woodhouse
2019-08-27 8:59 ` Jan Beulich
2019-08-27 9:19 ` David Woodhouse
2019-08-09 15:02 ` [Xen-devel] [PATCH v2 6/6] x86/boot: Do not use trampoline for no-real-mode boot paths David Woodhouse
2019-08-12 10:55 ` Jan Beulich
2019-08-19 15:25 ` David Woodhouse
2019-08-27 9:07 ` Jan Beulich [this message]
2019-08-27 9:12 ` David Woodhouse
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