| Message ID | 1426902601-13524-1-git-send-email-linux@rasmusvillemoes.dk (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sat, Mar 21 2015, Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > With CONFIG_DEBUG_INFO_REDUCED, we do get quite a lot of debug info > (around 22.7 MB for a defconfig+DEBUG_INFO_REDUCED). However, the > "basenames must match" rule used by -femit-struct-debug-baseonly > option means that we miss some core data structures, such as struct > {device, file, inode, mm_struct, page} etc. > > We can easily get these included as well, while still getting the > benefits of CONFIG_DEBUG_INFO_REDUCED (faster build times and smaller > individual object files): All it takes is a dummy translation unit > including a few strategic headers and compiled with a flag overriding > -femit-struct-debug-baseonly. > > This increases the size of .debug_info by ~0.3%, but these 90 KB > contain some rather useful info. > Any comments on this patch? I know it's a little hacky, but I do find it rather useful. For example, I just noticed that pahole shows this struct audit_names { struct list_head list; /* 0 0 */ /* XXX 16 bytes hole, try to pack */ when applied to a vmlinux built with DEBUG_INFO_REDUCED, since debug info for struct list_head is not included. The same is true for a lot of other types which are often embedded in structs (e.g. spinlock_t and atomic_t). I could of course just compile without DEBUG_INFO_REDUCED, but the time and space savings of that are real and sad to lose (my tree is 1.8 GB larger when I compile without it). Rasmus -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jun 11, 2015 at 02:32:48PM +0200, Rasmus Villemoes wrote: > On Sat, Mar 21 2015, Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote: > > > With CONFIG_DEBUG_INFO_REDUCED, we do get quite a lot of debug info > > (around 22.7 MB for a defconfig+DEBUG_INFO_REDUCED). However, the > > "basenames must match" rule used by -femit-struct-debug-baseonly > > option means that we miss some core data structures, such as struct > > {device, file, inode, mm_struct, page} etc. > > > > We can easily get these included as well, while still getting the > > benefits of CONFIG_DEBUG_INFO_REDUCED (faster build times and smaller > > individual object files): All it takes is a dummy translation unit > > including a few strategic headers and compiled with a flag overriding > > -femit-struct-debug-baseonly. > > > > This increases the size of .debug_info by ~0.3%, but these 90 KB > > contain some rather useful info. > > > > Any comments on this patch? I know it's a little hacky, but I do find it > rather useful. For example, I just noticed that pahole shows this I applied it to kbuild.git#kbuild now. It indeed can be quite useful. Michal -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/lib/Makefile b/lib/Makefile index 58f74d2dd396..3d788091d60c 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -45,6 +45,9 @@ CFLAGS_kobject.o += -DDEBUG CFLAGS_kobject_uevent.o += -DDEBUG endif +obj-$(CONFIG_DEBUG_INFO_REDUCED) += debug_info.o +CFLAGS_debug_info.o += $(call cc-option, -femit-struct-debug-detailed=any) + obj-$(CONFIG_GENERIC_IOMAP) += iomap.o obj-$(CONFIG_GENERIC_PCI_IOMAP) += pci_iomap.o obj-$(CONFIG_HAS_IOMEM) += iomap_copy.o devres.o diff --git a/lib/debug_info.c b/lib/debug_info.c new file mode 100644 index 000000000000..2edbe27517ed --- /dev/null +++ b/lib/debug_info.c @@ -0,0 +1,27 @@ +/* + * This file exists solely to ensure debug information for some core + * data structures is included in the final image even for + * CONFIG_DEBUG_INFO_REDUCED. Please do not add actual code. However, + * adding appropriate #includes is fine. + */ +#include <stdarg.h> + +#include <linux/cred.h> +#include <linux/crypto.h> +#include <linux/dcache.h> +#include <linux/device.h> +#include <linux/fs.h> +#include <linux/fscache-cache.h> +#include <linux/io.h> +#include <linux/kallsyms.h> +#include <linux/kernel.h> +#include <linux/kobject.h> +#include <linux/mm.h> +#include <linux/module.h> +#include <linux/net.h> +#include <linux/sched.h> +#include <linux/slab.h> +#include <linux/types.h> +#include <net/addrconf.h> +#include <net/sock.h> +#include <net/tcp.h>
With CONFIG_DEBUG_INFO_REDUCED, we do get quite a lot of debug info (around 22.7 MB for a defconfig+DEBUG_INFO_REDUCED). However, the "basenames must match" rule used by -femit-struct-debug-baseonly option means that we miss some core data structures, such as struct {device, file, inode, mm_struct, page} etc. We can easily get these included as well, while still getting the benefits of CONFIG_DEBUG_INFO_REDUCED (faster build times and smaller individual object files): All it takes is a dummy translation unit including a few strategic headers and compiled with a flag overriding -femit-struct-debug-baseonly. This increases the size of .debug_info by ~0.3%, but these 90 KB contain some rather useful info. Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk> --- lib/Makefile | 3 +++ lib/debug_info.c | 27 +++++++++++++++++++++++++++ 2 files changed, 30 insertions(+) create mode 100644 lib/debug_info.c