Acronyms & Definitions
|SATA||Serial Advanced Technology Attachement|
|PATA||Parallel AT Attachement|
|SSD||Solid State Disk|
|HDD||Hard Disk Drive|
|Gen-1/Gen-2/Gen-3||Generation of SATA device.|
Features NOT supported
- Gen-3 SATA HDD/SSD is not guaranteed to be supported on OMAP5 and DRA7 due to a silicon bug which prevents correct PHY speed negotiation.
- Aggressive Power management
|EVM||Number of Instances|
|AM57 GP EVM||1 Instance (either eSATA or mSATA)|
|Beagle X15||1 Instance (eSATA)|
|DRA74 GP EVM||1 Instance (SATA)|
Device Drivers ---> <M> Serial ATA and Parallel ATA drivers (libata) ---> <M> AHCI SATA support <M> Platform AHCI SATA support
Accessing SATA Hard Drive
These instructions assume the SATA hard drive being used has already been partitions. Information on partition the hard drive is beyond the scope of this article.
Detecting Hard Drive
Before you can start reading and writing to a partition you first need to know which sdX device is associate with the hard drive. The easiest approach is to use “parted -l”.
This command will show all the various storage medias Linux has detected. The output that will be shown may be quite large if you have sd cards, eMMC, USB thumbdrives, etc.. connected to the board. However, for SATA your only interested in devices that have “(scsi)” at the end of the Model field.
Example output of the command is shown below. Non SATA related output was truncated.
root@am57xx-evm:~# parted -l ... Model: ATA PLEXTOR PX-64M6M (scsi) Disk /dev/sda: 64.0GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 1 1049kB 83.9MB 82.8MB primary fat32 boot, lba 2 84.9MB 17.3GB 17.2GB primary fat32 3 17.3GB 64.0GB 46.8GB primary ext2 ...
Above the model field shows the name of the particular hard drive and in the disk field it shows the specific device (/dev/sdX) its associated with along with the size. In the above example this Plextor hard drive is associated with “/dev/sda”. The other additional information that can be gathered from the parted -l command is information regarding the various partitions. In the table that has column Number, Start, End, etc... you can see this hard drive has 3 partitions. The command shows various information including the partition size along with the file system type.
This is useful since each partition can be accessed via /dev/sdXY. Where X is the specific disk letter and Y is the partition number. Therefore, the device that is associated with the Plextor hard drive’s second partition is “/dev/sda2” which is a ~17GB FAT32 partition.
Determining Mounted Partition Location
Now its likely if you have partitions on the hard drive that their already been automated. Use “lsblk /dev/sdX” to determine if a partition has been mounted and if so where.
Example output of the command is shown below:
root@am57xx-evm:~# lsblk /dev/sda NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 59.6G 0 disk |-sda2 8:2 0 16G 0 part /run/media/sda2 |-sda3 8:3 0 43.6G 0 part `-sda1 8:1 0 79M 0 part /run/media/sda1
The above output shows the three sda partitions. Under mountpoint it list the directory that the partition has been mounted to. However, a blank entry under mount point indicates the partition has not been mounted.
Information regarding accessing SATA hard drive in U-boot can be found in the Linux Core U-boot User’s Guide SATA Section.