[Qemu-devel] [PATCH 11/11] m48t59: avoid structure holes spotted by pahole

[Blue Swirl]

Report from pahole on amd64 host:
struct M48t59State {
        uint32_t                   type;                 /*     0     4 */

        /* XXX 4 bytes hole, try to pack */

        qemu_irq                   IRQ;                  /*     8     8 */
        uint32_t                   io_base;              /*    16     4 */
        uint32_t                   size;                 /*    20     4 */
        time_t                     time_offset;          /*    24     8 */
        time_t                     stop_time;            /*    32     8 */
        struct tm                  alarm;                /*    40    56 */
        /* --- cacheline 1 boundary (64 bytes) was 32 bytes ago --- */
        struct QEMUTimer *         alrm_timer;           /*    96     8 */
        struct QEMUTimer *         wd_timer;             /*   104     8 */
        uint8_t                    lock;                 /*   112     1 */

        /* XXX 1 byte hole, try to pack */

        uint16_t                   addr;                 /*   114     2 */

        /* XXX 4 bytes hole, try to pack */

        uint8_t *                  buffer;               /*   120     8 */
        /* --- cacheline 2 boundary (128 bytes) --- */

        /* size: 128, cachelines: 2 */
        /* sum members: 119, holes: 3, sum holes: 9 */
};      /* definitions: 1 */

Fix by rearranging the structure to avoid padding.

Signed-off-by: Blue Swirl <address@hidden>
---
 hw/m48t59.c |    9 +++++----
 1 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/hw/m48t59.c b/hw/m48t59.c
index 537c0f7..67685cd 100644
--- a/hw/m48t59.c
+++ b/hw/m48t59.c
@@ -50,8 +50,6 @@
  */

 struct M48t59State {
-    /* Model parameters */
-    uint32_t type; // 2 = m48t02, 8 = m48t08, 59 = m48t59
     /* Hardware parameters */
     qemu_irq IRQ;
     uint32_t io_base;
@@ -64,9 +62,12 @@ struct M48t59State {
     struct QEMUTimer *alrm_timer;
     struct QEMUTimer *wd_timer;
     /* NVRAM storage */
-    uint8_t  lock;
-    uint16_t addr;
     uint8_t *buffer;
+    /* Model parameters */
+    uint32_t type; /* 2 = m48t02, 8 = m48t08, 59 = m48t59 */
+    /* NVRAM storage */
+    uint16_t addr;
+    uint8_t  lock;
 };

 typedef struct M48t59ISAState {
-- 
1.6.2.4

0011-m48t59-avoid-structure-holes-spotted-by-pahole.patch
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