target/alpha: Enable TARGET_PAGE_BITS_VARY for user-only

Since alpha binaries are generally built for multiple
page sizes, it is trivial to allow the page size to vary.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
Reviewed-by: Ilya Leoshkevich <iii@linux.ibm.com>
Acked-by: Helge Deller <deller@gmx.de>
Message-Id: <20240102015808.132373-34-richard.henderson@linaro.org>

target/alpha/cpu-param.h

@@ -9,10 +9,22 @@
 #define ALPHA_CPU_PARAM_H
 
 #define TARGET_LONG_BITS 64
-#define TARGET_PAGE_BITS 13
 
 /* ??? EV4 has 34 phys addr bits, EV5 has 40, EV6 has 44.  */
 #define TARGET_PHYS_ADDR_SPACE_BITS  44
-#define TARGET_VIRT_ADDR_SPACE_BITS  (30 + TARGET_PAGE_BITS)
+
+#ifdef CONFIG_USER_ONLY
+/*
+ * Allow user-only to vary page size.  Real hardware allows only 8k and 64k,
+ * but since any variance means guests cannot assume a fixed value, allow
+ * a 4k minimum to match x86 host, which can minimize emulation issues.
+ */
+# define TARGET_PAGE_BITS_VARY
+# define TARGET_PAGE_BITS_MIN 12
+# define TARGET_VIRT_ADDR_SPACE_BITS  63
+#else
+# define TARGET_PAGE_BITS 13
+# define TARGET_VIRT_ADDR_SPACE_BITS  (30 + TARGET_PAGE_BITS)
+#endif
 
 #endif