On Thu, Oct 18, 2018 at 08:06:05AM -0700, Matthew Wilcox wrote: > Can you name one that does require 512-byte alignment, preferably still > in use? Or even >4-byte alignment. I just checked AHCI and that requires > only 2-byte alignment. Xen-blkfront, rsxx, various SD/MMC card readers for example. > I have reason to believe that these are uncommon because of the feedback > we got in the NVMe committee after releasing 1.0 which required 4-byte > alignment from people whining that they just couldn't guarantee 4-byte > alignment in their host devices and they absolutely needed to have no > alignment requirements (!) See how things turned - after NVMe SGLs followed the no alignment rule enough controller vendors rebelled so that NVMe 1.3 has an option of SGL support only if 4-byte aligned.
