When building with -Werror=strict-aliasing error is thrown: mmc_cmds.c: In function 'do_ffu': mmc_cmds.c:2972:2: error: dereferencing type-punned pointer will break strict-aliasing rules [-Werror=strict-aliasing] sect_done = htole32(*((__u32 *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0])); ^ cc1: all warnings being treated as errors Let's fix type-punned breaking strict-aliasing by memcpy() the variable. Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx> --- mmc_cmds.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mmc_cmds.c b/mmc_cmds.c index ae7b876..dcd60aa 100644 --- a/mmc_cmds.c +++ b/mmc_cmds.c @@ -2968,7 +2968,8 @@ do_retry: } /* Test if we need to restart the download */ - sect_done = htole32(*((__u32 *)&ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0])); + memcpy(§_done, &ext_csd[EXT_CSD_NUM_OF_FW_SEC_PROG_0], sizeof(__u32)); + sect_done = htole32(sect_done); /* By spec, host should re-start download from the first sector if sect_done is 0 */ if (sect_done == 0) { if (retry--) { -- 2.34.1