mmc: Add erase, secure erase, trim and secure trim operations
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From: Andrew Morton on 30 Jun 2010 18:30 On Thu, 24 Jun 2010 11:44:00 +0300 Adrian Hunter <adrian.hunter(a)nokia.com> wrote: > SD/MMC cards tend to support an erase operation. In addition, > eMMC v4.4 cards can support secure erase, trim and secure trim > operations that are all variants of the basic erase command. The patch proposes a new userspace interface via sysfs, yes? Please fully describe that interface and its operation in the changelog. It'd also be nice to add permanent documentation for it. From reading the code, it appears that erase_size and preferred_erase_size have units in bytes. But users shouldn't need to read the code to find that out. What are the alignemnt and size requirements on these? What is their position in /sys? What do they actually *do* and what is the difference between them? etetera. People want to review this code and other people actually want to use it. I'm not sure that I want to try to review this code when nobody's told me what interface it implements and how it's supposed to work. Seems that whoever implemented BLKDISCARD didn't want anyone to use it either. Sigh. All of mmc core appears to use 32-bit quantities to represent sectors, yes? Why didn't it use sector_t? What are the implications of this? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Adrian Hunter on 1 Jul 2010 07:00
Andrew Morton wrote: > On Thu, 24 Jun 2010 11:44:00 +0300 > Adrian Hunter <adrian.hunter(a)nokia.com> wrote: > >> SD/MMC cards tend to support an erase operation. In addition, >> eMMC v4.4 cards can support secure erase, trim and secure trim >> operations that are all variants of the basic erase command. > > The patch proposes a new userspace interface via sysfs, yes? , Just two read-only values > > Please fully describe that interface and its operation in the > changelog. It'd also be nice to add permanent documentation for it. > OK >>From reading the code, it appears that erase_size and > preferred_erase_size have units in bytes. But users shouldn't need to > read the code to find that out. What are the alignemnt and size > requirements on these? What is their position in /sys? What do they > actually *do* and what is the difference between them? > > etetera. People want to review this code and other people actually > want to use it. I'm not sure that I want to try to review this code > when nobody's told me what interface it implements and how it's > supposed to work. Seems that whoever implemented BLKDISCARD didn't > want anyone to use it either. Sigh. > > > All of mmc core appears to use 32-bit quantities to represent sectors, > yes? Why didn't it use sector_t? What are the implications of this? SD/MMC addressing uses 32-bit values. There is a known 2TB limit for SD/MMC cards. As cards are only just getting to 64GB, that limit is some way off, and it is not clear NAND technology can get there in a SD/MMC package anyway. I don't know why sector_t is not used. I guess it would complicate doing division since it can be 64-bit. The implications are minimal. In the unlikely event SD/MMC cards ever exceed 2TB some changes will be needed, but the standard would have to change to allow that first. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |