[PULL 7/8] accel/tcg: only USE_STATIC_CODE_GEN_BUFFER on 32 bit hosts

[Richard Henderson <richard.henderson@linaro.org>]

From: Alex Bennée <alex.bennee@linaro.org>

There is no particular reason to use a static codegen buffer on 64 bit
hosts as we have address space to burn. Allow the common CONFIG_USER
case to use the mmap'ed buffers like SoftMMU.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Message-Id: <20200228192415.19867-4-alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 accel/tcg/translate-all.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c
index 5b66af783b..4ce5d1b393 100644
--- a/accel/tcg/translate-all.c
+++ b/accel/tcg/translate-all.c
@@ -892,11 +892,12 @@ static void page_lock_pair(PageDesc **ret_p1, tb_page_addr_t phys1,
     }
 }
 
-#if defined(CONFIG_USER_ONLY)
-/* Currently it is not recommended to allocate big chunks of data in
-   user mode. It will change when a dedicated libc will be used.  */
-/* ??? 64-bit hosts ought to have no problem mmaping data outside the
-   region in which the guest needs to run.  Revisit this.  */
+#if defined(CONFIG_USER_ONLY) && TCG_TARGET_REG_BITS == 32
+/*
+ * For user mode on smaller 32 bit systems we may run into trouble
+ * allocating big chunks of data in the right place. On these systems
+ * we utilise a static code generation buffer directly in the binary.
+ */
 #define USE_STATIC_CODE_GEN_BUFFER
 #endif
 
-- 
2.20.1