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[Xen-devel] Re: [patch 3/5] i386-gdt-pda Update lguest to initialize gdt

To: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
Subject: [Xen-devel] Re: [patch 3/5] i386-gdt-pda Update lguest to initialize gdt without pda
From: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Date: Tue, 27 Mar 2007 13:32:18 +1000
Cc: virtualization@xxxxxxxxxxxxxx, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Andi Kleen <ak@xxxxxxx>, Linux Kernel <linux-kernel@xxxxxxxxxxxxxxx>
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On Mon, 2007-03-26 at 17:21 -0700, Jeremy Fitzhardinge wrote:
> plain text document attachment (lguest-use-percpu.patch)

Thanks for the fixup Jeremy!

        Unfortunately that doesn't quite work.  But it turns out we don't need
to load the GDT at all: we can run off the Host-supplied one until we
load the gdt naturally.

So I prefer this patch:
Lguest now doesn't need to touch the GDT at all: it can run on the
Host-supplied boot gdt until it reloads later in the boot process.

Signed-off-by: Jeremy Fitzhardinge <jeremy@xxxxxxxxxxxxx>
Signed-off-by: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxx>
 arch/i386/lguest/lguest.c |   15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff -r 3349222e5f58 arch/i386/lguest/lguest.c
--- a/arch/i386/lguest/lguest.c Tue Mar 27 12:57:46 2007 +1000
+++ b/arch/i386/lguest/lguest.c Tue Mar 27 13:28:20 2007 +1000
@@ -34,7 +34,6 @@
 #include <asm/desc.h>
 #include <asm/setup.h>
 #include <asm/e820.h>
-#include <asm/pda.h>
 #include <asm/asm-offsets.h>
 #include <asm/mce.h>
@@ -448,10 +447,6 @@ static void lguest_power_off(void)
        hcall(LHCALL_CRASH, __pa("Power down"), 0, 0);
-/* From head.S */
-extern void setup_pda(void);
-extern struct Xgt_desc_struct early_gdt_descr;
 static __attribute_used__ __init void lguest_init(void)
@@ -513,11 +508,6 @@ static __attribute_used__ __init void lg
        /* We use top of mem for initial pagetables. */
        init_pg_tables_end = __pa(pg0);
-       /* set up PDA descriptor */
-       setup_pda();
-       load_gdt(&early_gdt_descr);
-       asm volatile ("mov %0, %%fs" : : "r" (__KERNEL_PDA) : "memory");

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