Re: [PATCH v3 13/13] ARM: imxrt_defconfig: add i.MXRT family defconfig

[Arnd Bergmann]

On Thu, Nov 25, 2021 at 10:14 PM Jesse Taube <mr.bossman075@xxxxxxxxx> wrote:
>
> From: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx>
>
> Add generic i.MXRT family defconfig.
>
> Signed-off-by: Giulio Benetti <giulio.benetti@xxxxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jesse Taube <Mr.Bossman075@xxxxxxxxx>

I see a lot of things in here that probably should not be part of the kernel,
either because they are rather obscure, or they take valuable memory:

> ---
>  arch/arm/configs/imxrt_defconfig | 157 +++++++++++++++++++++++++++++++
>  1 file changed, 157 insertions(+)
>  create mode 100644 arch/arm/configs/imxrt_defconfig
>
> diff --git a/arch/arm/configs/imxrt_defconfig b/arch/arm/configs/imxrt_defconfig
> new file mode 100644
> index 000000000000..d673745a5462
> --- /dev/null
> +++ b/arch/arm/configs/imxrt_defconfig
> @@ -0,0 +1,157 @@
> +# CONFIG_LOCALVERSION_AUTO is not set
> +CONFIG_SYSVIPC=y
> +CONFIG_USELIB=y

You almost certainly won't want USELIB, and SYSVIPC support
would only be useful for certain applications that you probably
won't run.

> +CONFIG_BSD_PROCESS_ACCT=y
> +CONFIG_BSD_PROCESS_ACCT_V3=y
> +CONFIG_PSI=y
> +CONFIG_IKCONFIG=y
> +CONFIG_IKCONFIG_PROC=y

Probably nonen of these are helpful here.

> +CONFIG_MEMCG=y
> +CONFIG_BLK_CGROUP=y
> +CONFIG_CFS_BANDWIDTH=y
> +CONFIG_CGROUP_PIDS=y
> +CONFIG_CGROUP_RDMA=y
> +CONFIG_CGROUP_FREEZER=y
> +CONFIG_CGROUP_DEVICE=y
> +CONFIG_CGROUP_CPUACCT=y
> +CONFIG_CGROUP_PERF=y
> +CONFIG_CGROUP_BPF=y
> +CONFIG_NAMESPACES=y
> +CONFIG_USER_NS=y
> +CONFIG_CHECKPOINT_RESTORE=y

Same for control groups overall as well as checkpoint_restore

> +CONFIG_RELAY=y

There are a few drivers using CONFIG_RELAY, but I don't see you enable
any of them,
so this is not actually used.

> +CONFIG_EXPERT=y

Are you losing anything without EXPERT? If not, remove that

> +CONFIG_SGETMASK_SYSCALL=y
> +# CONFIG_FUTEX is not set

Futex is probably one of the things you /do/ want.

> +CONFIG_KALLSYMS_ALL=y
> +CONFIG_PC104=y

Turning off KALLSYMS_ALL may save a noticeable amount of RAM.

PC104 isn't actually that big, but it seems unlikely that you have
that hardware.

> +CONFIG_PARAVIRT=y

You don't seem to enable XEN, so I don't think PARAVIRT is useful by itself.

> +# CONFIG_ATAGS is not set
> +CONFIG_CMDLINE="console=ttyS0 root=/dev/mmcblk0p2 rw earlycon rootwait"

The command line should come from the boot loader, users probably have
a different root device.

> +CONFIG_BLK_DEV_BSGLIB=y
> +CONFIG_BLK_DEV_INTEGRITY=y
> +CONFIG_BLK_DEV_ZONED=y
> +CONFIG_BLK_DEV_THROTTLING=y
> +CONFIG_BLK_WBT=y
> +CONFIG_BLK_SED_OPAL=y
> +CONFIG_PARTITION_ADVANCED=y
> +CONFIG_BSD_DISKLABEL=y
> +CONFIG_MINIX_SUBPARTITION=y
> +CONFIG_SOLARIS_X86_PARTITION=y
> +CONFIG_UNIXWARE_DISKLABEL=y
> +CONFIG_LDM_PARTITION=y

I don't see you using OPAL or any of the 1990's partition formats.
ot set

> +CONFIG_BINFMT_FLAT=y

For the defconfig, you should probably have ELF_FDPIC enabled,
not just FLAT.

> +CONFIG_CLEANCACHE=y
> +CONFIG_ZPOOL=y
> +CONFIG_ZBUD=y
> +CONFIG_Z3FOLD=y

Do these work as expected on NOMMU?

> +CONFIG_BLK_DEV_LOOP=y
> +CONFIG_BLK_DEV_RAM=y
> +CONFIG_BLK_DEV_RAM_COUNT=1
> +CONFIG_BLK_DEV_RAM_SIZE=65536

I don't think you can have a ramdisk larger than RAM ;-)

> +CONFIG_MEMORY=y

No need to enable the subsystem when you don't enable any
of its drivers.

> +CONFIG_EXT2_FS=y
> +CONFIG_EXT2_FS_XATTR=y
> +CONFIG_EXT2_FS_POSIX_ACL=y
> +CONFIG_EXT2_FS_SECURITY=y
> +CONFIG_EXT3_FS=y
> +CONFIG_EXT3_FS_POSIX_ACL=y
> +CONFIG_EXT3_FS_SECURITY=y

Never use EXT3 on eMMC, just use EXT4 instead to make
the device actually live longer. You probably don't need to enable
EXT2 support separately.

> +# CONFIG_FILE_LOCKING is not set
> +# CONFIG_DNOTIFY is not set
> +CONFIG_QUOTA=y

dnotify and locking seem more useful than quota here

> +# CONFIG_PRINT_QUOTA_WARNING is not set
> +CONFIG_AUTOFS4_FS=y

> +CONFIG_CONFIGFS_FS=y

I don't see anything using configfs

> +CONFIG_LSM="yama,loadpin,integrity,apparmor"

None of these are actually enabled as far as I can tell.

> +CONFIG_DEBUG_INFO=y
> +CONFIG_DEBUG_INFO_DWARF4=y

If you use DWARF4, you probably want DEBUG_INFO_SPLIT as well,
to reduce the vmlinux size.

       Arnd