[Qemu-devel] [QEMU] Windows XP / Windows 95 / MS-DOS 6 regressions

["Hervé Poussineau" <hpoussin@reactos.org>]

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Hi,

I currently see some regressions on Microsoft operating systems.

1) Windows XP bugchecks since commit:
commit 7f0b7141b4c7deab51efd8ee1e83eab2d9b7a9ea
Author: Richard Henderson <rth@twiddle.net>
Date:   Mon Jul 6 17:29:59 2015 +0100

     target-i386: Perform set/reset_inhibit_irq inline

     With helpers that can be reused for other things.

     Signed-off-by: Richard Henderson <rth@twiddle.net>

I'm starting QEMU with -cpu pentium2.
Attached patch can be applied on master to work-around the problem.
Another work-around is to start with -enable-kvm.

2) Windows 95 bugchecks since commit:
commit d6a2914984c89fa0a3125b9842e0cbf68de79a3d
Author: Richard Henderson <rth@twiddle.net>
Date:   Thu Dec 17 11:19:19 2015 -0800

     target-i386: Use gen_lea_v_seg in gen_lea_modrm

     Centralize handling of segment bases.

     Signed-off-by: Richard Henderson <rth@twiddle.net>
     Message-Id: <1450379966-28198-4-git-send-email-rth@twiddle.net>
     Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

(with 88c73d16ad1b6c22a2ab082064d0d521f756296a and 4987783400667147ada01a5bdcce53f11b822888 cherry-picked)

I'm starting QEMU with -cpu pentium.
I've not searched for a work-around.

3) MS-DOS 6 freezes when loading himem.sys since commit:
commit 1906b2af7c2345037d9b2fdf484b457b5acd09d1
Author: Richard Henderson <rth@twiddle.net>
Date: Thu Jul 2 13:59:21 2015 +0100

     target-i386: Rearrange processing of 0F 01

     Rather than nesting tests of OP, MOD, and RM, decode them
     all at once with a switch. Fixes incorrect decoding of
     AMD Pacifica extensions (aka vmrun et al) via op==2 path.

     Signed-off-by: Richard Henderson <rth@twiddle.net>

I'm starting QEMU with -cpu 486.
It works on master if I add -enable-kvm

Hervé

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>From 0e66ca87ac7c94219ab49cfbed6f586c51c697de Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Herv=C3=A9=20Poussineau?= <hpoussin@reactos.org>
Date: Sun, 28 Feb 2016 15:00:29 +0100
Subject: [PATCH] target-i386: partially revert 'Perform set/reset_inhibit_irq
 inline'

This partially reverts commit 7f0b7141b4c7deab51efd8ee1e83eab2d9b7a9ea to fix Windows XP.
---
 target-i386/cc_helper.c | 5 +++++
 target-i386/helper.h    | 1 +
 target-i386/translate.c | 3 ++-
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/target-i386/cc_helper.c b/target-i386/cc_helper.c
index 83af223..e6f4fe9 100644
--- a/target-i386/cc_helper.c
+++ b/target-i386/cc_helper.c
@@ -383,3 +383,8 @@ void helper_sti_vm(CPUX86State *env)
     }
 }
 #endif
+
+void helper_set_inhibit_irq(CPUX86State *env)
+{
+    env->hflags |= HF_INHIBIT_IRQ_MASK;
+}
diff --git a/target-i386/helper.h b/target-i386/helper.h
index e33451a..bdba6bd 100644
--- a/target-i386/helper.h
+++ b/target-i386/helper.h
@@ -70,6 +70,7 @@ DEF_HELPER_1(cli, void, env)
 DEF_HELPER_1(sti, void, env)
 DEF_HELPER_1(clac, void, env)
 DEF_HELPER_1(stac, void, env)
+DEF_HELPER_1(set_inhibit_irq, void, env)
 DEF_HELPER_3(boundw, void, env, tl, int)
 DEF_HELPER_3(boundl, void, env, tl, int)
 DEF_HELPER_1(rsm, void, env)
diff --git a/target-i386/translate.c b/target-i386/translate.c
index 9171929..4ec94b9 100644
--- a/target-i386/translate.c
+++ b/target-i386/translate.c
@@ -6780,7 +6780,8 @@ static target_ulong disas_insn(CPUX86State *env, DisasContext *s,
                 /* interruptions are enabled only the first insn after sti */
                 /* If several instructions disable interrupts, only the
                    _first_ does it */
-                gen_set_hflag(s, HF_INHIBIT_IRQ_MASK);
+                if (!(s->tb->flags & HF_INHIBIT_IRQ_MASK))
+                    gen_helper_set_inhibit_irq(cpu_env);
                 /* give a chance to handle pending irqs */
                 gen_jmp_im(s->pc - s->cs_base);
                 gen_eob(s);
-- 
2.1.4