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From 1dfb44fecec3070163d66047815f3cbebabfceb6 Mon Sep 17 00:00:00 2001
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From: Radim Krcmar <rkrcmar@redhat.com>
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Date: Mon, 10 Mar 2014 15:14:27 +0100
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Subject: Workaround for a win8.1-32 S4 resume bug
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Radim Krcmar <rkrcmar@redhat.com>
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Message-id: <1394464467-23560-1-git-send-email-rkrcmar@redhat.com>
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Patchwork-id: 58069
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O-Subject: [RHEL7.0 seabios PATCH] Workaround for a win8.1-32 S4 resume bug
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Bugzilla: 1050775
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RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>
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RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
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RH-Acked-by: Laszlo Ersek <lersek@redhat.com>
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bug: https://bugzilla.redhat.com/show_bug.cgi?id=1050775
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brew: http://brewweb.devel.redhat.com/brew/taskinfo?taskID=7176174
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This patch has no upstream equivalent.
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When a 32 bit version of windows 8.1 resumes from suspend, it writes 1
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into 0x72 in the early boot because it didn't expect a NULL pointer.
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0x72 is lower offset byte of 0x1c interrupt entry, so we jump into a
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middle of other function if this interrupt is triggered.
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Because 0x1c is only triggered from our handle_08, we detect if our
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default value (function that does only iret) has its lower offset byte
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overwritten and skip it in that case.
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(Windows never sets own callback there, so we always detect this bug
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correctly, as seabios doesn't use it either
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Other sources shouldn't incorrectly overwrite it or use seabios code,
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but it is quite ok even if the guest did this on purpose.)
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The reason Windows uses NULL pointer is still unknown, but this bug is
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blocking WHQL certification, so we have to work around it in 7.0.
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Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
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---
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src/clock.c | 8 +++++++-
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1 file changed, 7 insertions(+), 1 deletion(-)
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diff --git a/src/clock.c b/src/clock.c
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index e44e112..298a722 100644
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--- a/src/clock.c
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+++ b/src/clock.c
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@@ -309,7 +309,13 @@ handle_08(void)
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struct bregs br;
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memset(&br, 0, sizeof(br));
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br.flags = F_IF;
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- call16_int(0x1c, &br);
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+ struct segoff_s isr1c = GET_IVT(0x1c);
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+ // hardcoded address of entry_iret_official with lower segment byte
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+ // overwritten by 1
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+ if (isr1c.seg == ((SEG_BIOS & ~0xff) | 0x1) && isr1c.offset == 0xff53)
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+ dprintf(1, "Worked around win8.1-32 S4 resume bug\n");
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+ else
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+ call16_int(0x1c, &br);
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pic_eoi1();
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}
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--
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1.8.3.1
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