[Qemu-devel] [PATCH] linux-user: use arm features based on cpu model

[Qemu-devel] [PATCH] linux-user: use arm features based on cpu model

[Lars Munch]

Use arm features based on cpu model. The hardcoded feature list gave
problems in the setjmp/longjmp functions of glibc since it tried to use
VFP instructions even though I specified a pxa270 as cpu model.

Signed-off-by: Lars Munch <lars@segv.dk>
---
 linux-user/elfload.c |   10 ++++++----
 1 files changed, 6 insertions(+), 4 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 91eea62..79af51d 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -333,10 +333,12 @@ enum
   ARM_HWCAP_ARM_VFPv3D16  = 1 << 13,
 };
 
-#define ELF_HWCAP (ARM_HWCAP_ARM_SWP | ARM_HWCAP_ARM_HALF              \
-                    | ARM_HWCAP_ARM_THUMB | ARM_HWCAP_ARM_FAST_MULT     \
-                    | ARM_HWCAP_ARM_FPA | ARM_HWCAP_ARM_VFP \
-                    | ARM_HWCAP_ARM_NEON | ARM_HWCAP_ARM_VFPv3 )
+#define ELF_HWCAP get_elf_hwcap()
+
+static uint32_t get_elf_hwcap(void)
+{
+    return thread_env->features;
+}
 
 #endif
 
-- 
1.7.0

Re: [Qemu-devel] [PATCH] linux-user: use arm features based on cpu model

[Paul Brook]

> +static uint32_t get_elf_hwcap(void)
> +{
> +    return thread_env->features;
> +}

No.  These values are not the same.

Paul

Re: [Qemu-devel] [PATCH] linux-user: use arm features based on cpu model

[Lars Munch]

On Mon, Mar 15, 2010 at 12:26:27PM +0000, Paul Brook wrote:
> > +static uint32_t get_elf_hwcap(void)
> > +{
> > +    return thread_env->features;
> > +}
> 
> No.  These values are not the same.
> 
> Paul
>

Yes, these values are indeed not the same. Below is an updated patch with a
function similar to the PPC get_elf_hwcap function. I am unsure if I have too
many or too few features as I do not know the details on all the capability
flags, so comments are more than welcome.

Signed-off-by: Lars Munch <lars@segv.dk>
---
 linux-user/elfload.c |   24 ++++++++++++++++++++----
 1 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index 91eea62..6364176 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -333,10 +333,26 @@ enum
   ARM_HWCAP_ARM_VFPv3D16  = 1 << 13,
 };
 
-#define ELF_HWCAP (ARM_HWCAP_ARM_SWP | ARM_HWCAP_ARM_HALF              \
-                    | ARM_HWCAP_ARM_THUMB | ARM_HWCAP_ARM_FAST_MULT     \
-                    | ARM_HWCAP_ARM_FPA | ARM_HWCAP_ARM_VFP \
-                    | ARM_HWCAP_ARM_NEON | ARM_HWCAP_ARM_VFPv3 )
+#define ELF_HWCAP get_elf_hwcap()
+
+static uint32_t get_elf_hwcap(void)
+{
+    CPUARMState *e = thread_env;
+    uint32_t features = ARM_HWCAP_ARM_SWP | ARM_HWCAP_ARM_HALF
+      | ARM_HWCAP_ARM_THUMB | ARM_HWCAP_ARM_FAST_MULT
+      | ARM_HWCAP_ARM_FPA;
+
+#define GET_FEATURE(flag, feature)              \
+    do {if (e->features & flag) features |= feature; } while(0)
+    GET_FEATURE(ARM_FEATURE_VFP, ARM_HWCAP_ARM_VFP);
+    GET_FEATURE(ARM_FEATURE_IWMMXT, ARM_HWCAP_ARM_IWMMXT);
+    GET_FEATURE(ARM_FEATURE_NEON, ARM_HWCAP_ARM_NEON);
+    GET_FEATURE(ARM_FEATURE_VFP3, ARM_HWCAP_ARM_VFPv3);
+    GET_FEATURE(ARM_FEATURE_VFP_FP16, ARM_HWCAP_ARM_VFPv3D16);
+#undef GET_FEATURE
+
+    return features;
+}
 
 #endif
 
-- 
1.7.0