[Qemu-devel] [PATCH 05/11] tcx: avoid structure holes spotted by pahole

[Blue Swirl]

Report from pahole on amd64 host:
struct TCXState {
        SysBusDevice               busdev;               /*     0  5648 */
        /* --- cacheline 88 boundary (5632 bytes) was 16 bytes ago --- */
        target_phys_addr_t         addr;                 /*  5648     8 */
        DisplayState *             ds;                   /*  5656     8 */
        uint8_t *                  vram;                 /*  5664     8 */
        uint32_t *                 vram24;               /*  5672     8 */
        uint32_t *                 cplane;               /*  5680     8 */
        ram_addr_t                 vram_offset;          /*  5688     8 */
        /* --- cacheline 89 boundary (5696 bytes) --- */
        ram_addr_t                 vram24_offset;        /*  5696     8 */
        ram_addr_t                 cplane_offset;        /*  5704     8 */
        uint32_t                   vram_size;            /*  5712     4 */
        uint16_t                   width;                /*  5716     2 */
        uint16_t                   height;               /*  5718     2 */
        uint16_t                   depth;                /*  5720     2 */
        uint8_t                    r[256];               /*  5722   256 */
        /* --- cacheline 93 boundary (5952 bytes) was 26 bytes ago --- */
        uint8_t                    g[256];               /*  5978   256 */
        /* --- cacheline 97 boundary (6208 bytes) was 26 bytes ago --- */
        uint8_t                    b[256];               /*  6234   256 */

        /* XXX 2 bytes hole, try to pack */

        /* --- cacheline 101 boundary (6464 bytes) was 28 bytes ago --- */
        uint32_t                   palette[256];         /*  6492  1024 */
        /* --- cacheline 117 boundary (7488 bytes) was 28 bytes ago --- */
        uint8_t                    dac_index;            /*  7516     1 */
        uint8_t                    dac_state;            /*  7517     1 */

        /* size: 7520, cachelines: 118 */
        /* sum members: 7516, holes: 1, sum holes: 2 */
        /* padding: 2 */
        /* last cacheline: 32 bytes */
};      /* definitions: 1 */

Fix by rearranging the structure to avoid padding.

Signed-off-by: Blue Swirl <address@hidden>
---
 hw/tcx.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/tcx.c b/hw/tcx.c
index 0e32830..309600d 100644
--- a/hw/tcx.c
+++ b/hw/tcx.c
@@ -42,9 +42,9 @@ typedef struct TCXState {
     uint32_t *vram24, *cplane;
     ram_addr_t vram_offset, vram24_offset, cplane_offset;
     uint32_t vram_size;
-    uint16_t width, height, depth;
-    uint8_t r[256], g[256], b[256];
     uint32_t palette[256];
+    uint8_t r[256], g[256], b[256];
+    uint16_t width, height, depth;
     uint8_t dac_index, dac_state;
 } TCXState;

-- 
1.6.2.4

0005-tcx-avoid-structure-holes-spotted-by-pahole.patch
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