Electronic device including a memory technology device

Patent metadata

Field	Value
Publication number	US-9507584-B2
Application number	US-201414554148-A
Country	US
Kind code	B2
Filing date	Nov 26, 2014
Priority date	Nov 28, 2013
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

The electronic device may include a RAM, a nonvolatile storage device as an MTD, and firmware that may be stored on the nonvolatile storage device. The firmware may include a kernel that is expanded onto the RAM and a root disk image as a root file system. The kernel mounts the root disk image on the nonvolatile storage device as the root file system when a boot mode of the electronic device is a normal boot mode. The kernel, when the boot mode is an update mode for updating the firmware on the nonvolatile storage device, may i) generate a RAM disk as an MTD in an area of the RAM not under management of the kernel, ii) expand the root disk image on the nonvolatile storage device into the RAM disk, and iii) mount the root disk image on the RAM disk as the root file system.

First claim

What is claimed is:

1. An electronic device, comprising:
a central processing unit (CPU);
a random access memory (RAM) that is used as a work area for the CPU; and
a flash memory as a nonvolatile storage device that acts as a memory technology device (MTD), wherein the flash memory has stored thereon firmware for an open-source code operating system, and the firmware comprises:
a boot loader that is expanded onto the RAM from the flash memory by the CPU, when the electronic device is booted, and determines whether a boot mode of the electronic device is an update mode for updating the firmware in the flash memory, or a normal mode;
a kernel that is expanded onto the RAM from the flash memory by the boot loader; and
only one root disk image, as a compressed file of a root file system, that includes a file that has a format read by the kernel from the MTD via a read-only file system,
wherein the only one root disk image on the flash memory is used both when the boot mode is the normal boot mode and when the boot mode is the update mode,
wherein the kernel, when notified by the boot loader that the boot mode of the electronic device is the normal boot mode, mounts the root disk image on the flash memory as the root file system, and the mounted root disk image is read into an area of the RAM not under management of the kernel in unit of a page, and
wherein the kernel, when notified by the boot loader that the boot mode is the update mode, i) generates a RAM disk as the MTD in the area of the RAM not under management of the kernel, ii) expands the root disk image on the flash memory into the RAM disk, iii) mounts the root disk image on the RAM disk as the root file system, iv) the root disk image is read into the area of the RAM not under the management of the kernel in unit of the page, and v) the CPU, in accordance with the root disk image on the RAM disk, deletes the firmware before update from the flash memory, and then writes the firmware after update into the flash memory.

2. The electronic device according to claim 1 ,
wherein the file included in the root disk image has the format that can be read by the kernel from the MTD via the read-only file system such as Cramfs or Squashfs.

3. A method by an electronic device that includes i) a central processing unit (CPU); ii) a random access memory (RAM) that is used as a work area for the CPU; and iii) a flash memory as a nonvolatile storage device that acts as a memory technology device (MTD), the method comprising:
providing a firmware for an open-source code operating system on the flash memory, wherein the firmware comprises a boot loader, a kernel, and only one root disk image as a compressed file of a root file system, including a file that has a format read by the kernel from the MTD via a read-only file system;
expanding, via the CPU, the boot loader from the flash memory onto the RAM, when the electronic device is booted;
expanding, via the boot loader, the kernel from the flash memory onto the RAM;
determining, via the boot loader, whether a boot mode of the electronic device is an update mode for updating the firmware on the flash memory, or a normal mode;
mounting, via the kernel, the root disk image on the flash memory as the root file system, when notified by the boot loader that the boot mode of the electronic device is the normal boot mode, wherein the mounted root disk image is read into an area of the RAM not under management of the kernel in unit of a page;
generating, via the kernel, a RAM disk as the MTD in the area of the RAM not under management of the kernel, when notified by the boot loader that the boot mode is the update mode;
expanding, via the kernel, the root disk image on the flash memory into the RAM disk;
mounting, via the kernel, the root disk image on the a RAM disk as the root file system, wherein the root disk image is read into the area of the RAM not under the management of the kernel in unit of the page; and
deleting, via the CPU in accordance with the root disk image on the RAM disk, deleting the firmware before update from the flash memory, and then writing the firmware after update into the flash memory,
wherein the only one root disk image on the flash memory is used in common when the boot mode is the normal boot mode and when the boot mode is the update mode.

4. A non-transitory computer-readable medium having a program, the program causing a central processing unit (CPU), in an electronic device that includes a random access memory (RAM) that is used as a work area for the CPU; and a flash memory as a nonvolatile storage device that acts as a memory technology device (MTD), to perform the following operations:
providing a firmware for an open-source code operating system on the flash memory, wherein the firmware comprises a boot loader, a kernel, and only one root disk image as a compressed file of a root file system, including a file that has a format read by the kernel from the MTD via a read-only file system;
expanding, via the CPU, the boot loader from the flash memory onto the RAM, when the electronic device is booted;
expanding, via the boot loader, the kernel from the flash memory onto the RAM;
determining, via the boot loader, whether a boot mode of the electronic device is an update mode for updating the firmware on the flash memory, or a normal mode;
mounting, via the kernel, the root disk image on the flash memory as the root file system, when notified by the boot loader that the boot mode of the electronic device is the normal boot mode, wherein the mounted root disk image is read into an area of the RAM not under management of the kernel in unit of a page;
generating, via the kernel, a RAM disk as the MTD in the area of the RAM not under management of the kernel, when notified by the boot loader that the boot mode is the update mode;
expanding, via the kernel, the root disk image on the flash memory into the RAM disk;
mounting, via the kernel, the root disk image on the a RAM disk as the root file system, wherein the root disk image is read into the area of the RAM not under the management of the kernel in unit of the page; and
deleting, via the CPU in accordance with the root disk image on the RAM disk, the firmware before update from the flash memory, and then writing the firmware after update into the flash memory,
wherein the only one root disk image on the flash memory is used in common when the boot mode is the normal boot mode and when the boot mode is the update mode.

Assignees

• Kyocera Document Solutions Inc

Inventors

• Tsuji Shuntaro

Classifications

• G06F8/665 Primary

  Physics · mapped topic

• G06F9/441

  Multiboot arrangements, i.e. selecting an operating system to be loaded · CPC title

• G06F8/654 Primary

  using techniques specially adapted for alterable solid state memories, e.g. for EEPROM or flash memories · CPC title