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Re: [Qemu-devel] [PATCH] hw/acpi: fix Q35 support for legacy Windows OS

From: Marcel Apfelbaum
Subject: Re: [Qemu-devel] [PATCH] hw/acpi: fix Q35 support for legacy Windows OS
Date: Mon, 7 Mar 2016 17:43:14 +0200
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0

On 03/07/2016 05:16 PM, Igor Mammedov wrote:
On Mon, 7 Mar 2016 15:21:44 +0200
Marcel Apfelbaum <address@hidden> wrote:

On 03/07/2016 02:36 PM, Michael S. Tsirkin wrote:
On Mon, Mar 07, 2016 at 01:06:43PM +0100, Igor Mammedov wrote:
On Sun,  6 Mar 2016 14:17:56 +0200
Marcel Apfelbaum <address@hidden> wrote:

Legacy Windows operating systems like Windows XP and Windows 2003
require _DIS method to be present for all interrupt links.

PC machines already have a no-op implemented for GSI links, add
it also in Q35.
Maybe I don't see but only LINKS has no-op _DIS, the rest of
links have _DIS that does something. According to spec
_STA must return disabled status after _DIS has been called.

A no-op _DIS is OK as long as the interrupt can not be disabled.
Marcel, how about a comment explaining this?

Sure, I'll add a comment and re-post.

BTW, going over it again:
- we really need to set separate UIDs for them, might
    be a good idea to fix that, might it not?

Absolutely (in my opinion), Igor is OK if I'll submit a patch for it?
Since we're getting rid of old Q35 machines we don't care about compatibility 
Sure, provided Windows doesn't complain/crash.

I'll be sure to check enough Windows guests,

      method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
      aml_append(method, aml_create_dword_field(aml_arg(0), aml_int(5), 
      aml_append(method, aml_store(aml_name("PRRI"), reg));
      aml_append(dev, method);

should this be serialized as it creates a local name (PRRI)?
I'd make it serialize for other reason,
it shouldn't happen but what if method were executed in parallel

I'll let Igor answer this.


Signed-off-by: Marcel Apfelbaum <address@hidden>


I tested this patch with WinXP and Win 2003, but also with Win 10, and Fedora.
This solves a BSOD early in the setup process.

WinXP/2003 can be tested using:
       -device piix3-ide,id=legacyide \
       -drive file=winxp-q35.qcow2,if=none,id=disk -device 
ide-hd,drive=disk,bus=legacyide.0 \
       -drive file=xp_sp3.iso,if=none,id=cdrom -device 

Please note that you have to use the piix3-ide because Win2003 (and probably XP)
does not have Q35 AHCI drivers inbox.


   hw/i386/acpi-build.c | 3 +++
   1 file changed, 3 insertions(+)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 52c9470..4c66568 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1509,6 +1509,9 @@ static Aml *build_gsi_link_dev(const char *name, uint8_t 
uid, uint8_t gsi)

       aml_append(dev, aml_name_decl("_CRS", crs));

+    method = aml_method("_DIS", 0, AML_NOTSERIALIZED);
+    aml_append(dev, method);
       method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
       aml_append(dev, method);

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