Date: Mon, 13 Apr 2009 11:56:09 +0100 From: Chris Rees <utisoft@googlemail.com> To: perryh@pluto.rain.com Cc: freebsd@edvax.de, freebsd-questions@freebsd.org Subject: Re: USB SD-card reader recognized, but not working, on 6.1 Message-ID: <b79ecaef0904130356k681b9096w1c07cd18dad6e17@mail.gmail.com> In-Reply-To: <49deb5d1.syt1ug/OWLKGHOGd%perryh@pluto.rain.com> References: <49de2c9a.QlCBOleCO/iBrMcf%perryh@pluto.rain.com> <20090409181009.GA38361@slackbox.xs4all.nl> <49de50cb.gcYrr9F1eSmdUBu9%perryh@pluto.rain.com> <20090410003759.dede9c9e.freebsd@edvax.de> <49deb5d1.syt1ug/OWLKGHOGd%perryh@pluto.rain.com>
next in thread | previous in thread | raw e-mail | index | archive | help
2009/4/10 <perryh@pluto.rain.com>: > Polytropon <freebsd@edvax.de> wrote: >> On Thu, 09 Apr 2009 12:47:23 -0700, perryh@pluto.rain.com wrote: >> > It's an SD card, not a "drive", so I had not expected it to be >> > partitioned; but yes, it is: >> > >> > $ ls -l /dev/da0* >> > crw-r----- =A01 root =A0operator =A0 =A00, 244 Feb 14 15:09 /dev/da0 >> > crw-r----- =A01 root =A0operator =A0 =A00, 245 Feb 14 15:09 /dev/da0s1 >> >> Why don't you expect this? As far as I know, if something is >> msdosfs-formatted (read: any "Windows" readable file system, >> FAT), it always involves a "slice device". I never found a >> situation where access to /dev/da0 would work. > > My experience is exactly the reverse. =A0I've never before seen a > removable-media device (floppy, Zip-drive, JAZ drive) that *did* > have a DOS "partition" table aka BSD "slice" table. =A0Surely you > would not expect a USB floppy to show up as /dev/da0s1? > > AFAIK the reason for creating slices is to identify sections of > the device for use by different OS -- something often needed > for multi-boot from a hard drive but seldom on removable media. > I sure wasn't planning to use part of this SD card for my camera > to store pictures on, and the rest for FreeBSD backups :) Aha, careful. A flash drive/card is more like a removable hard drive. Since it's so much bigger than a floppy etc (typically) it makes sense to have a proper slice (partition) structure. If you want to boot off a floppy, it's a different operation from booting off a HDD for precisely this reason. Whereas a floppy isn't a proper, 'fixed' type disk; it's a tiny thing, suitable for max ~10 files. There's no need to have the overhead of a partition table, MBR etc. Same with CDs, booting off them involves several strange fudges (El Torito). Since a flash card would be a sensible thing to boot off, the designers want it to look more like a hard drive; as well as having the flexibility. Chris --=20 A: Because it messes up the order in which people normally read text. Q: Why is top-posting such a bad thing? A: Top-posting. Q: What is the most annoying thing in e-mail?
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?b79ecaef0904130356k681b9096w1c07cd18dad6e17>