Hi, On 2023-03-22 15:51, Ard Biesheuvel wrote: > On Tue, 21 Mar 2023 at 23:26, Aurelien Jarno <aurelien@xxxxxxxxxxx> wrote: > > > > Hi, > > > > On 2022-10-13 08:35, Masahiro Yamada wrote: > > > In the previous discussion (see the Link tag), Ard pointed out that > > > arm/arm64/kernel/head.o does not need any special treatment - the only > > > piece that must appear right at the start of the binary image is the > > > image header which is emitted into .head.text. > > > > > > The linker script does the right thing to do. The build system does > > > not need to manipulate the link order of head.o. > > > > > > Link: https://lore.kernel.org/lkml/CAMj1kXH77Ja8bSsq2Qj8Ck9iSZKw=1F8Uy-uAWGVDm4-CG=EuA@xxxxxxxxxxxxxx/ > > > Suggested-by: Ard Biesheuvel <ardb@xxxxxxxxxx> > > > Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx> > > > --- > > > > > > scripts/head-object-list.txt | 1 - > > > 1 file changed, 1 deletion(-) > > > > > > diff --git a/scripts/head-object-list.txt b/scripts/head-object-list.txt > > > index b16326a92c45..f226e45e3b7b 100644 > > > --- a/scripts/head-object-list.txt > > > +++ b/scripts/head-object-list.txt > > > @@ -15,7 +15,6 @@ arch/alpha/kernel/head.o > > > arch/arc/kernel/head.o > > > arch/arm/kernel/head-nommu.o > > > arch/arm/kernel/head.o > > > -arch/arm64/kernel/head.o > > > arch/csky/kernel/head.o > > > arch/hexagon/kernel/head.o > > > arch/ia64/kernel/head.o > > > > This patch causes a significant increase of the arch/arm64/boot/Image > > size. For instance the generic arm64 Debian kernel went from 31 to 39 MB > > after this patch has been applied to the 6.1 stable tree. > > > > In turn this causes issues with some bootloaders, for instance U-Boot on > > a Raspberry Pi limits the kernel size to 36 MB. > > > > I cannot reproduce this with mainline > > With the patch > > $ size vmlinux > text data bss dec hex filename > 24567309 14752630 621680 39941619 26175f3 vmlinux > > With the patch reverted > > $ size vmlinux > text data bss dec hex filename > 24567309 14752694 621680 39941683 2617633 vmlinux I have tried with the current mainline, this is what I get, using GCC 12.2.0 and binutils 2.40: text data bss dec hex filename 32531655 8192996 621968 41346619 276e63b vmlinux.orig 25170610 8192996 621968 33985574 2069426 vmlinux.revert > It would help to compare the resulting vmlinux ELF images from both > builds to see where the extra space is being allocated At a first glance, it seems the extra space is allocated in the BTF section. I have uploaded the resulting files as well as the config file I used there: https://temp.aurel32.net/linux-arm64-size-head.o.tar.gz -- Aurelien Jarno GPG: 4096R/1DDD8C9B aurelien@xxxxxxxxxxx http://www.aurel32.net
