[PATCH 04/10] cpu: Add a way to detect 32-bit mode from argv0

[Thomas Huth <thuth@redhat.com>]

From: Thomas Huth <thuth@redhat.com>

In the future, we might want to avoid compiling certain targets separately
for 32-bit mode (i.e. -i386, -arm and -ppc) where the 64-bit variant is a
superset of the 32-bit variant. But it would be good to provide a way to
mimic the 32-bit behavior via the program name in case the users need this
compatibility for some scenarios. Thus add a function that checks
for the old 32-bit program names and sets a flag accordingly.

Signed-off-by: Thomas Huth <thuth@redhat.com>
---
 include/qemu/target-info.h |  7 +++++++
 system/vl.c                |  1 +
 target-info.c              | 20 ++++++++++++++++++--
 3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/include/qemu/target-info.h b/include/qemu/target-info.h
index 0713ab4bb16..aa9b2e9b0cf 100644
--- a/include/qemu/target-info.h
+++ b/include/qemu/target-info.h
@@ -9,6 +9,13 @@
 #ifndef QEMU_TARGET_INFO_H
 #define QEMU_TARGET_INFO_H
 
+/**
+ * target_info_adjust:
+ *
+ * Returns: Adjust the target according to the binary name of the executable.
+ */
+void target_info_adjust(const char *argv0);
+
 /**
  * target_name:
  *
diff --git a/system/vl.c b/system/vl.c
index 246623b3196..45c9f5d5c7a 100644
--- a/system/vl.c
+++ b/system/vl.c
@@ -2884,6 +2884,7 @@ void qemu_init(int argc, char **argv)
 
     error_init(argv[0]);
     qemu_init_exec_dir(argv[0]);
+    target_info_adjust(argv[0]);
 
     os_setup_limits();
 
diff --git a/target-info.c b/target-info.c
index dea73b5fbca..b18fd4e0060 100644
--- a/target-info.c
+++ b/target-info.c
@@ -12,6 +12,21 @@
 #include "qemu/target-info-impl.h"
 #include "qapi/error.h"
 
+static bool force_32bit;
+
+void target_info_adjust(const char *argv0)
+{
+    switch (target_arch()) {
+    case SYS_EMU_TARGET_X86_64:
+        if (g_str_has_suffix(argv0, "-i386")) {
+            force_32bit = true;
+        }
+        break;
+    default:
+        break;
+    }
+}
+
 const char *target_name(void)
 {
     return target_info()->target_name;
@@ -107,10 +122,11 @@ bool target_base_x86(void)
 
 bool target_i386(void)
 {
-    return target_arch() == SYS_EMU_TARGET_I386;
+    return target_arch() == SYS_EMU_TARGET_I386 ||
+           (target_arch() == SYS_EMU_TARGET_X86_64 && force_32bit);
 }
 
 bool target_x86_64(void)
 {
-    return target_arch() == SYS_EMU_TARGET_X86_64;
+    return target_arch() == SYS_EMU_TARGET_X86_64 && !force_32bit;
 }
-- 
2.53.0