Memtest86-usb.img: x86 boot sector partition 1: ID=0xee, starthead 0, startsector 1, 307199 sectors, code offset 0xc0Īt first its partition layout looked pretty odd to me: $ fdisk memtest86-usb.imgĭisk: memtest86-usb.img geometry: 609/8/63 Here are some of its properties, information which would later be useful.Ĭhecking the image file itself, notice that it’s actually a hard drive image: $ file memtest86-usb.img Unlike many of the Linux distribution images, which come as ISO files, memtest86 came already designed for USB booting. In fact, there were two EFI Boot entries, which both worked – more on that later. Worked perfectly! (No memory errors, by the way.
Holding down Option while booting brought up the Startup Manager, which allowed me to select EFI Boot. Unmount of all volumes on disk2 was successful
I downloaded the memtest86 bootable USB image, then used diskutil to find and prepare my USB stick, and dd to copy the memtest86 image to my USB device: $ diskutil listģ: Apple_Boot Recovery HD 650.0 MB disk0s3Ġ: Apple_HFS Macintosh HD *499.1 GB disk1 The first thing I wanted to try was memtest86.