[lfs-dev] eudev has replaced systemd in LFS

Bruce Dubbs bruce.dubbs at gmail.com
Sat Mar 8 09:47:36 PST 2014


William Harrington wrote:
>
> On Mar 7, 2014, at 7:00 PM, William Harrington wrote:

> I talked to Armin and looked up the Changes between Util linux 2.20
> and 2.21 and found that findmnt and lsblk include udev support. Not
> sure what more info would be presented with udev support, but I now
> see the reason more clearly.
>
> https://www.kernel.org/pub/linux/utils/util-linux/v2.21/v2.21-ReleaseNotes

FYI.  From Karel Zak 1/8/14

   -- Bruce

> Let me add that util-linux builds very nicely when building up the
> different packages in Linux From Scratch. In our sequence when
> util-linux is built, we have not yet built udev (we extract only the
> udev portion out of the systemd tarball, but do that later). At that
> point we have:

 > $ ldd /bin/findmnt
 >         linux-vdso.so.1 (0x00007fffdebff000)
 >         libmount.so.1 => /lib/libmount.so.1 (0x00007fe5c4563000)
 >         libblkid.so.1 => /lib/libblkid.so.1 (0x00007fe5c432a000)
 >         libuuid.so.1 => /lib/libuuid.so.1 (0x00007fe5c4126000)
 >         libc.so.6 => /lib/libc.so.6 (0x00007fe5c3d7c000)
 >         /lib64/ld-linux-x86-64.so.2 (0x00007fe5c479f000)
 >
 > Looking at the code, it's not clear to me what extra functionality
 > get_tag_from_udev() provides.

  That's simple -- you don't need root permissions to read from udev,
  but you need root permissions to parse filesystem/PT on the device
  by libblkid.

  udev has also more information collected from more sources, see for
  example lsblk.c where non-udev part does not provide WWN and serial
  number.

  It's also better if all system use information from one place (udev),
  so libblkid is fallback solution here (in findmnt, lsblk).



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