1# 64 byte NVMe, Read command (a NVM command) that is suitable for: 2# sg_raw --cmdfile=<this_file_name> --nvm --request=2048 <nvme_device> 3# 4# The address field (at byte offset 24, 8 bytes and little endian) gives 5# special meaning to the highest address pointers: 6# ffffffff fffffffe use address of data-in buffer 7# ffffffff fffffffd use address of data-out buffer 8# 9# The data length field (at byte offset 36, 4 bytes and little endian) 10# gives special meaning to the highest block counts: 11# fffffffe use byte length of data-in buffer 12# fffffffd use byte length of data-out buffer 13# 14# 512 byte logical block size is assumed. Read 4 blocks hence 2048 bytes. 15# The first LBA read is 0x12345 and the namespace is 1. If successful 16# the four blocks will be read into the data-in buffer. Submission queue 17# 0 is used (the same queue that Admin commands use). The NVM opcode for 18# the Read command is 0x2 and appears in the first command byte. 19 2002 00 00 00 01 00 00 00 00 00 00 00 00 00 00 00 2100 00 00 00 00 00 00 00 fe ff ff ff ff ff ff ff 2200 00 00 00 fe ff ff ff 45 23 01 00 00 00 00 00 2303 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 24 25# Notice NVMe uses its quirky "0's based" number of blocks so 26# 03 appears at byte offset 48 to mean "read 4 blocks". 27# 28# A typical invocation in Linux and FreeBSD would look like this: 29# sg_raw --cmdfile=nvme_read_ctl.hex --nvm -r 2048 30# --outfile=t.bin /dev/nvme0n1 31# In FreeBSD the device name would be /dev/nvme0ns1 32# 33# Notice the '--nvm' option which is needed to distinguish a NVM 34# command from an Admin command as Admin commands are the default 35# in this utility. 36# 37# This utility (and most others in the package) aligns data-in and 38# data-out buffers to the beginning of pages which are 4096 bytes 39# long at a minimum. This is the way NVMe likes things as well. 40