From 3e68fbb59b3d4e6b47b65e9928b5929e02179759 Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Mon, 15 May 2006 00:49:43 +0100 Subject: [JFFS2] Don't pack on-medium structures, because GCC emits crappy code If we use __attribute__((packed)), GCC will _also_ assume that the structures aren't sensibly aligned, and it'll emit code to cope with that instead of straight word load/save. This can be _very_ suboptimal on architectures like ARM. Ideally, we want an attribute which just tells GCC not to do any padding, without the alignment side-effects. In the absense of that, we'll just drop the 'packed' attribute and hope that everything stays as it was (which to be fair is fairly much what we expect). And add some paranoia checks in the initialisation code, which should be optimised away completely in the normal case. Signed-off-by: David Woodhouse --- include/linux/jffs2.h | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'include/linux/jffs2.h') diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h index cf792bb..228ad72 100644 --- a/include/linux/jffs2.h +++ b/include/linux/jffs2.h @@ -82,15 +82,15 @@ typedef struct { uint32_t v32; -} __attribute__((packed)) jint32_t; +} jint32_t; typedef struct { uint32_t m; -} __attribute__((packed)) jmode_t; +} jmode_t; typedef struct { uint16_t v16; -} __attribute__((packed)) jint16_t; +} jint16_t; struct jffs2_unknown_node { @@ -99,7 +99,7 @@ struct jffs2_unknown_node jint16_t nodetype; jint32_t totlen; /* So we can skip over nodes we don't grok */ jint32_t hdr_crc; -} __attribute__((packed)); +}; struct jffs2_raw_dirent { @@ -117,7 +117,7 @@ struct jffs2_raw_dirent jint32_t node_crc; jint32_t name_crc; uint8_t name[0]; -} __attribute__((packed)); +}; /* The JFFS2 raw inode structure: Used for storage on physical media. */ /* The uid, gid, atime, mtime and ctime members could be longer, but @@ -149,7 +149,7 @@ struct jffs2_raw_inode jint32_t data_crc; /* CRC for the (compressed) data. */ jint32_t node_crc; /* CRC for the raw inode (excluding data) */ uint8_t data[0]; -} __attribute__((packed)); +}; struct jffs2_raw_summary { @@ -163,7 +163,7 @@ struct jffs2_raw_summary jint32_t sum_crc; /* summary information crc */ jint32_t node_crc; /* node crc */ jint32_t sum[0]; /* inode summary info */ -} __attribute__((packed)); +}; union jffs2_node_union { -- cgit v1.1 From ba9627b85fcb5ed67285ca0711f0f4d1e965746e Mon Sep 17 00:00:00 2001 From: David Woodhouse Date: Tue, 16 May 2006 23:03:08 +0100 Subject: [JFFS2] Repack some on-medium structures. ARM is weirder than I thought. We have to pack at least the jint16_t structure, because otherwise it'll be four bytes in size. Thankfully, we can do that and _not_ pack the actual node structures, and the compiler still doesn't emit stupid code. Signed-off-by: David Woodhouse --- include/linux/jffs2.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'include/linux/jffs2.h') diff --git a/include/linux/jffs2.h b/include/linux/jffs2.h index 228ad72..a26fbd4 100644 --- a/include/linux/jffs2.h +++ b/include/linux/jffs2.h @@ -82,15 +82,15 @@ typedef struct { uint32_t v32; -} jint32_t; +} __attribute__((packed)) jint32_t; typedef struct { uint32_t m; -} jmode_t; +} __attribute__((packed)) jmode_t; typedef struct { uint16_t v16; -} jint16_t; +} __attribute__((packed)) jint16_t; struct jffs2_unknown_node { -- cgit v1.1