Re: [Xen-devel] [PATCH] [HVMLOADER] built-in memcmp function uses not-yet implemented opcode

[Stefan Berger <stefanb@xxxxxxxxxx>]

xen-devel-bounces@xxxxxxxxxxxxxxxxxxx wrote on 11/29/2006
02:51:50 AM:

> On 29/11/06 4:15 am, "Stefan Berger" <stefanb@xxxxxxxxxx>
wrote:
> 
> >   it seems like the acpi/build.c function now uses the gcc
built-in
> > memcmp function. Unfortunately that one seems to generate some
code that
> > hits a not-yet implemented/emulated opcode. Instead of implementing
> > emultaion for that opcode I just copied the previously used memcmp
> > function from util.c into the build.c and renamed it to _memcmp
to avoid
> > linking problems.
> 
> There's an easier fix. hvmloader/acpi/Makefile is missing -fno-builtin.
I'll
> apply a patch.

I had tried that, but it didn't help, either, and
memcmp got linked in. Maybe this fix here is ok?

--- build.c          
      2006-11-29 07:12:51.000000000 -0500
+++ build.c.new              
  2006-11-29 00:21:38.000000000 -0500
@@ -116,6 +116,7 @@ int construct_secondary_tables(uint8_t *
     struct acpi_20_madt *madt;
     struct acpi_20_tcpa *tcpa;
     static const uint16_t tis_did_vid_rid[] = {0x0001, 0x0001,
0x0001};
+    uint16_t *mem16;
 
     /* MADT. */
     if ( (get_vcpu_nr() > 1) || get_apic_mode() )
@@ -126,8 +127,10 @@ int construct_secondary_tables(uint8_t *
     }
 
     /* TPM TCPA and SSDT. */
-    if ( memcmp((char *)0xFED40F00, tis_did_vid_rid,
-                sizeof(tis_did_vid_rid))
== 0 ) /* Probe for TIS interface. */
+    mem16 = (uint16_t *)0xFED40F00;
+    if (mem16[0] == tis_did_vid_rid[0] &&
+        mem16[1] == tis_did_vid_rid[1] &&
+        mem16[2] == tis_did_vid_rid[2]) 
     {
         memcpy(&buf[offset], AmlCode_TPM, sizeof(AmlCode_TPM));
         table_ptrs[nr_tables++] = (unsigned long)&buf[offset];


   Stefan
> 
>  Thanks,
>  Keir
> 
> 
> 
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