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RE: [Xen-devel] A useless short jmp?
- To: "Keir Fraser" <keir@xxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
- From: "Li, Xin B" <xin.b.li@xxxxxxxxx>
- Date: Tue, 19 Jun 2007 10:03:42 +0800
- Delivery-date: Mon, 18 Jun 2007 19:02:13 -0700
- List-id: Xen developer discussion <xen-devel.lists.xensource.com>
- Thread-index: AcexsWxtRnqse1ngRRSVOXIcWSiSzwADXzoNABVnA0A=
- Thread-topic: [Xen-devel] A useless short jmp?
>> According to Intel Spec, it's useless, do we have any
>special reason to
>> have it there?
>> BTW why put mov $1, %bl between lmsw and it's corresponding ljmp?
>Hmmm... I'm sure I read somewhere about a jmp to clear the
Surely you did read it :-), in the latest Spec (version of May 2007),
in17.29.3 Enabling and Disabling Paging, it's said a near jump should be
executed after set or clear PG flag in CR0, but it's a different case
since we are setting or clearing PE flag, probably plus PG changes too.
>but reading the appropriate manual pages now I see I only need
>I'll fix that and also move the write to %bx somewhere more sensible.
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