Actually as of the current kernel, uas support/driver is a prerequisite of TRIM, because skip_vdp_page in scsiglue.c prevent sd_read_block_limits(), which configure various values necessary for blkdev_issue_discard() (and other filesystem-specific discard functions/ioctls) through sd_config_discard().
On 15 June 2015 at 22:37, Alan Stern <st...@rowland.harvard.edu> wrote: > On Mon, 15 Jun 2015, Tom Yan wrote: > >> I have a SanDisk Extreme USB Flash Drive >> (http://www.sandisk.com/products/usb/drives/extreme/), which does NOT >> support UASP so is running under "usb-storage". >> >> According to `hdparm`, it seems to supports TRIM; and according to >> `sg3_opcodes`, it seems to support ATA Pass-Through (12/16). However, >> all TRIM/DISCARD related ioctl doesn't work with it at all. >> >> So my question is, is TRIM/DISCARD possible at all in linux for usb >> drives? If so, what are the requirements? If not, is it just not >> implemented yet or an inherit problem of usb which cannot be fixed? > > This has nothing to do with USB. It's simply a question of whether or > not that particular flash drive implements the command. Some drives do > and and some don't. > > Alan Stern > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
