Re: [Qemu-discuss] Mac access to sse4.2 x86 extentions

[Eric Fronberg]

 I've been able to resolve my issues and wonder whether there are better

ways other than my hack.  I expect this is the wrong place but I wanted to put this out for other

qemu'ers

All changes made to target-i386/cpu.c 

mmacbookpro-enf:~ enf$ diff -c ~/Downloads/qemu-1.2.0/target-i386/cpu.c ~/src/play/c/qemu-1.2.0/target-i386/cpu.c

*** /Users/enf/Downloads/qemu-1.2.0/target-i386/cpu.c 2012-09-05 07:03:06.000000000 -0700

--- /Users/enf/src/play/c/qemu-1.2.0/target-i386/cpu.c 2012-11-01 19:32:19.000000000 -0700

***************

*** 116,122 ****

  void host_cpuid(uint32_t function, uint32_t count,

                  uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)

  {

! #if defined(CONFIG_KVM)

      uint32_t vec[4];

  

  #ifdef __x86_64__

--- 116,122 ----

  void host_cpuid(uint32_t function, uint32_t count,

                  uint32_t *eax, uint32_t *ebx, uint32_t *ecx, uint32_t *edx)

  {

! #if defined(CONFIG_KVM) || defined(__APPLE__)

      uint32_t vec[4];

  

  #ifdef __x86_64__

***************

*** 273,279 ****

            CPUID_VME, CPUID_DTS, CPUID_SS, CPUID_HT, CPUID_TM, CPUID_PBE */

  #define TCG_EXT_FEATURES (CPUID_EXT_SSE3 | CPUID_EXT_MONITOR | \

            CPUID_EXT_CX16 | CPUID_EXT_POPCNT | \

!           CPUID_EXT_HYPERVISOR)

            /* missing:

            CPUID_EXT_DTES64, CPUID_EXT_DSCPL, CPUID_EXT_VMX, CPUID_EXT_EST,

            CPUID_EXT_TM2, CPUID_EXT_XTPR, CPUID_EXT_PDCM, CPUID_EXT_XSAVE */

--- 273,279 ----

            CPUID_VME, CPUID_DTS, CPUID_SS, CPUID_HT, CPUID_TM, CPUID_PBE */

  #define TCG_EXT_FEATURES (CPUID_EXT_SSE3 | CPUID_EXT_MONITOR | \

            CPUID_EXT_CX16 | CPUID_EXT_POPCNT | \

!           CPUID_EXT_HYPERVISOR | CPUID_EXT_SSE42)

            /* missing:

            CPUID_EXT_DTES64, CPUID_EXT_DSCPL, CPUID_EXT_VMX, CPUID_EXT_EST,

            CPUID_EXT_TM2, CPUID_EXT_XTPR, CPUID_EXT_PDCM, CPUID_EXT_XSAVE */

-- Eric

On Nov 1, 2012, at 3:53 PM, Eric Fronberg <address@hidden> wrote:

I'm running into problems with qemu.  I tend to pack my emails with lots of data (trying to identify 

the issue first)

Installed on my early 2011 macbook pro via MacPorts. (v1.2.0)  I've verified that sse4.2 functionality is

available on this mac.

I'm using the following command to invoke.

/usr/local/bin/qemu-system-x86_64 -cpu SandyBridge,+sse,+sse4_2,+xsave,+avx,check   -device e1000,netdev=mynet0 -serial telnet::4446,server -m 768M -vga std -hda /Users/enf/enf-default.img -netdev user,id=mynet0 -hdc /dev/null

Qemu comes up but complains about 

...

warning: host cpuid 0000_0001 lacks requested flag 'sse4.1|sse4_1' [0x00080000]

warning: host cpuid 0000_0001 lacks requested flag 'sse4.2|sse4_2' [0x00100000]

...

Issue 1 (?)

-------

I downloaded the source code and noticed that host_cpuid will ALWAYS return 0 as CONFIG_KVM

is not defined.  This seems wrong.  ( I hacked up the code to comment out the CONFIG_KVM and 

I don't see the warnings any more).  Seems that the cpuid in the mac (bsd) environment has been

dummied down.  Is this correct.

Issue 2 

-------

Even with code that retrieves the correct cpuid, I run into a problem.

Running code that uses some of the sse4.2 x86 extensions but gets an invalid opcode error

when trying to execute the sse4.2 instructions.

Note that the same code works on a non VM system.  

Issue3 (related probably to issue 2)

------

Again running the modified qemu code, I'm getting the hostid directly to see if sse4.2 functionally

is present.  Call returns back that VM doesn't support sse4.2.

So it would seem that beyond the host_cpuid() function, there are additional limitations on the instruction

set in the VM.

How do I get qemu to give me a more fully functional emulation?

thanks!

-- Eric

Eric Fronberg

Sr. Software Engineer

Tel: +1(650) 730 5185

address@hidden

Coraid: Redefining Storage