Re: [PATCH v2 21/21] riscv: Add Canaan Kendryte K210 SD card defconfig

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

Hi Damien,

On Tue, Nov 24, 2020 at 5:39 AM Damien Le Moal <damien.lemoal@xxxxxxx> wrote:
> The nommu_k210_defconfig default configuration allows booting a K210
> SoC based board using an embedded intramfs cpio file. Modifying this
> configuration to enable support for the board SD card is not
> trivial for all users. To help beginners getting started with this
> board, add the nommu_k210_sdcard_defconfig default configuration file
> to set all configuration options necessary to use the board mmc-spi
> sd card for the root file system. This configuration adds support for
> the block layer, the mmc-spi driver and modifies the boot options to
> specify the rootfs device as mmcblk0p1 (first partition of the sd card
> block device). The ext2 file system is selected by default to encourage
> its use as that results in only about 4KB added to the kernel image
> size. The default device tree compiled in is unchanged and must be
> replaced by the user with the device tree suitable for the board being
> used (k210_maix_bit, k210_maix_dock, k210_maix_go, k210_maixduino or
> k210_kd233).
>
> Signed-off-by: Damien Le Moal <damien.lemoal@xxxxxxx>

While ext2 is definitely cheaper than ext4 (the latter takes almost +200
KiB, ugh), ext2 does not have journaling.
Hence your root file system will be unclean all the time, unless you always
manage to unmount it before reboot.  And your default buildroot
does not have e2fsck.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds