On Tue, Feb 04, 2020 at 11:22:19AM +0900, Masahiro Yamada wrote: > Hi. > > On Tue, Feb 4, 2020 at 6:16 AM Arvind Sankar <nivedita@xxxxxxxxxxxx> wrote: > > > > If the kernel is going to be compressed anyway, there is no point in > > double-compressing the built-in initramfs. Hide the built-in initramfs > > compression choice in this case. > > > > Signed-off-by: Arvind Sankar <nivedita@xxxxxxxxxxxx> > > > Double-compression slightly reduces the data size. > And, keeping the bare vmlinux small is beneficial, IMHO. > Ok. In my setup (kernel is compressed by xz), none for the builtin initramfs is optimal by a measurable amount, but I that will depend on config/initramfs contents/compression methods, so might well not be true in general. Maybe add a note to the help text? none 7030816 arch/x86/boot/bzImage gz 7382144 arch/x86/boot/bzImage bz2 7353696 arch/x86/boot/bzImage lzma 7118176 arch/x86/boot/bzImage xz 7126400 arch/x86/boot/bzImage lzo 7379360 arch/x86/boot/bzImage lz4 7335712 arch/x86/boot/bzImage diff --git a/usr/Kconfig b/usr/Kconfig index a6b68503d177..b68910b225fc 100644 --- a/usr/Kconfig +++ b/usr/Kconfig @@ -125,6 +125,12 @@ choice low on RAM, since it reduces the memory consumption during boot. + Note that if the kernel itself is compressed, the builtin initramfs + will be compressed twice, first by the algorithm selected here, and + then by the kernel compression method chosen. This may increase the + final image size, so you should test whether compressing the builtin + initramfs provides any savings. + Keep in mind that your build system needs to provide the appropriate compression tool to compress the generated initram cpio file for embedding.
