Hello.

My ARM Chromebook SNOW model has the mmc slot broken,but I've realized

that I can boot Linux using the USB port ! To enable the booting of Linux via USB

I have modified this file :

https://github.com/virtualopensystems/u-boot/blob/eecfeb578e296ef3b739ac918a...

in this way :

/* * Copyright (C) 2013 - Virtual Open Systems * Author: Nikolay Nikolaev n.nikolaev@virtualopensystems.com * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License, version 2, as * published by the Free Software Foundation. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */

#ifndef __configs_snow_h__ #define __configs_snow_h__

#include <configs/smdk5250.h>

#undef CONFIG_DEFAULT_DEVICE_TREE #define CONFIG_DEFAULT_DEVICE_TREE exynos5250-snow

/* Generally verified boot needs more heap space */ #undef CONFIG_SYS_MALLOC_LEN #define CONFIG_SYS_MALLOC_LEN (32 << 20)

#define CONFIG_INITRD_ADDRESS 0x44000000

#include <configs/chromeos.h>

/* Disable ChromeOS specifics */ #undef CONFIG_CHROMEOS

/* Force reading the environment */ #undef CONFIG_OF_LOAD_ENVIRONMENT

#define CONFIG_CHROMEOS_USB

/* Support vboot flag reading from GPIO hardwrae */ #define CONFIG_CHROMEOS_GPIO_FLAG

/* Support vboot flag reading from EC */ #define CONFIG_CHROMEOS_MKBP_FLAG

/* Use the default arch_phys_memset implementation */ #define CONFIG_PHYSMEM

/* Adjust the display resolution. */ #undef MAIN_VRESOL_VAL #undef MAIN_HRESOL_VAL #define MAIN_VRESOL_VAL 0x300 #define MAIN_HRESOL_VAL 0x556 #undef LCD_XRES #undef LCD_YRES #define LCD_XRES 1366 #define LCD_YRES 768 #define CONFIG_SYS_WHITE_ON_BLACK

/* * Extra bootargs used for direct booting, but not for vboot. * - console of the board * - debug and earlyprintk: easier to debug; they could be removed later */ #define CONFIG_DIRECT_BOOTARGS \ "console=tty1 debug clk_ignore_unused"

/* Standard input, output and error device of U-Boot console. */ #define CONFIG_STD_DEVICES_SETTINGS EXYNOS_DEVICE_SETTINGS

#define CONFIG_CHROMEOS_SD_TO_SPI \ "sd_to_spi=echo Flashing U-Boot from SD card to SPI flash; " \ "if mmc dev 1 && " \ "mmc rescan && " \ "mmc read 40008000 1 1000 && " \ "sf probe 1:0 && " \ "sf update 40008000 0 80000; then " \ "echo Flash completed; else " \ "echo Flash failed; " \ "fi\0"

/* Replace default CONFIG_EXTRA_ENV_SETTINGS */ #ifdef CONFIG_EXTRA_ENV_SETTINGS #undef CONFIG_EXTRA_ENV_SETTINGS #endif #define CONFIG_EXTRA_ENV_SETTINGS \ EXYNOS_DEVICE_SETTINGS \ "dtaddr=0x43000000\0"\ "initrdaddr=0x44000000\0"\ "boot_noinitrd=usb start ; usb dev 0 ; ext2load usb 0:2 ${loadaddr} uImage ; ext2load usb 0:2 ${dtaddr} exynos5250-snow.dtb ; bootm ${loadaddr} - ${dtaddr}\0"\ "boot_initrd=usb start ; usb dev 0 ; ext2load usb 0:2 ${loadaddr} uImage ; ext2load usb 0:2 ${initrdaddr} initrd ; ext2load usb 0:2 ${dtaddr} exynos5250-snow.dtb ; bootm ${loadaddr} ${initrdaddr} ${dtaddr}\0"\ "bootdelay=10\0"

#ifdef CONFIG_BOOTARGS #undef CONFIG_BOOTARGS #endif #define CONFIG_BOOTARGS \ "console=tty1 root=/dev/da0p4 rw rootwait clk_ignore_unused --no-log"

/* Replace default CONFIG_BOOTCOMMAND */ #ifdef CONFIG_BOOTCOMMAND #undef CONFIG_BOOTCOMMAND #endif #define CONFIG_BOOTCOMMAND \ "run boot_noinitrd"

/* Enable splash screens */ #define CONFIG_CROS_SPLASH

/* Enable simple framebuffer */ #define CONFIG_SIMPLEFB

/* Enable writing on a FAT formatted filesystem */ #define CONFIG_FAT_WRITE

/* Enable virt mode commands */ #define CONFIG_ARMV7_VIRT

/* Disable d-cache */ #define CONFIG_SYS_DCACHE_OFF

#endif /* __configs_snow_h__ */

I have modified mmc with usb 0 and I've changed the timeout from "bootdelay=3\0"

to "bootdelay=10\0" and I ran the script that located here :

https://github.com/virtualopensystems/u-boot/blob/eecfeb578e296ef3b739ac918a...

that creates a new : nv_uboot-snow-usb.kpart file,that I install on the sd card where

I have installed Linux,using the following commands :

# dd if=/dev/zero of=/dev/sdi1 dd: writing to '/dev/sdi1': No space left on device 32769+0 records in 32768+0 records out 16777216 bytes (17 MB, 16 MiB) copied, 2.07775 s, 8.1 MB/s

# sudo dd if=nv_uboot-snow-usb.kpart of=/dev/sdi1

At this point I attach the usb to sd card converter on the Chromebook and I try to

boot Linux,but to my surprise I see that the bootloader is still set to 3 seconds.

It means that for some reason,the new nv_uboot-snow-usb.kpart is not detected,

because when I have recompiled it,I have chosen 10 seconds of timeout for u-boot.

I really don't have any idea of the reasons why the new settings aren't applied.