arm_sync_file_range - Linux

Overview

arm_sync_file_range is a Linux command that provides a method for synchronizing data between the host system and an Arm-based device over an Arm System Management Interface (SMI) channel. It allows for the selective transfer of data to or from a specific file or file range within the device’s memory. This command is commonly used in debugging and maintenance scenarios or when exchanging data between the host and the device.

Syntax

arm_sync_file_range /dev/arm_smmu <action> <flags> <device_address> <host_address> <num_bytes> [<offset>]

Options/Flags

  • -r: Read data from the device.
  • -w: Write data to the device.
  • -c: Copy data from the device to the host.
  • -m: Map the device’s memory into the host’s virtual address space.
  • -u: Unmap the device’s memory from the host’s virtual address space.
  • -f: File descriptor of the file to be synchronized.
  • -o: Offset within the file to start synchronization.

Examples

Example 1: Read 1024 bytes from the device’s memory at address 0x1000 and save it to a file:

arm_sync_file_range /dev/arm_smmu -r -f my_file.bin -d 0x1000 -h 1024

Example 2: Write 2048 bytes to the device’s memory at address 0x2000 from a file:

arm_sync_file_range /dev/arm_smmu -w -f my_file.bin -d 0x2000 -h 2048

Example 3: Map the device’s memory region starting at address 0x3000 into the host’s virtual address space:

arm_sync_file_range /dev/arm_smmu -m -d 0x3000

Common Issues

  • Ensure that the arm_smmu module is loaded in the kernel.
  • Check that the device is properly connected and configured.
  • Verify that the specified file exists and is accessible.
  • Ensure that the specified device address and size are valid.

Integration

arm_sync_file_range can be used in conjunction with other commands to automate tasks. For instance, it can be combined with dd to create a disk image from a device:

arm_sync_file_range /dev/arm_smmu -r -f my_image.img -d 0x0 -h <disk size> | dd of=/dev/sdx

Related Commands

  • arm_smmu: Provides access to the SMU control registers.
  • dd: A utility for copying and converting data.
  • fsync: Forces the write of data from the host to the device.