13. What to do when UML doesn't work
13.1 Strange compilation errors when you build from source
- 13.2 UML hangs on boot after mounting devfs
+ 13.2 (obsolete)
13.3 A variety of panics and hangs with /tmp on a reiserfs filesystem
13.4 The compile fails with errors about conflicting types for 'open', 'dup', and 'waitpid'
13.5 UML doesn't work when /tmp is an NFS filesystem
bug fixes and enhancements that have gone into subsequent releases.
- If you build your own kernel, and want to boot it from one of the
- filesystems distributed from this site, then, in nearly all cases,
- devfs must be compiled into the kernel and mounted at boot time. The
- exception is the SuSE filesystem. For this, devfs must either not be
- in the kernel at all, or "devfs=nomount" must be on the kernel command
- line. Any disagreement between the kernel and the filesystem being
- booted about whether devfs is being used will result in the boot
- getting no further than single-user mode.
-
-
- If you don't want to use devfs, you can remove the need for it from a
- filesystem by copying /dev from someplace, making a bunch of /dev/ubd
- devices:
-
-
- UML# for i in 0 1 2 3 4 5 6 7; do mknod ubd$i b 98 $i; done
-
-
-
-
- and changing /etc/fstab and /etc/inittab to refer to the non-devfs
- devices.
-
-
-
2\b2.\b.2\b2.\b. C\bCo\bom\bmp\bpi\bil\bli\bin\bng\bg a\ban\bnd\bd i\bin\bns\bst\bta\bal\bll\bli\bin\bng\bg k\bke\ber\brn\bne\bel\bl m\bmo\bod\bdu\bul\ble\bes\bs
UML modules are built in the same way as the native kernel (with the
+\bo None - device=none
- This causes the device to disappear. If you are using devfs, the
- device will not appear in /dev. If not, then attempts to open it
- will return -ENODEV.
+ This causes the device to disappear.
- 1\b13\b3.\b.2\b2.\b. U\bUM\bML\bL h\bha\ban\bng\bgs\bs o\bon\bn b\bbo\boo\bot\bt a\baf\bft\bte\ber\br m\bmo\bou\bun\bnt\bti\bin\bng\bg d\bde\bev\bvf\bfs\bs
-
- The boot looks like this:
-
-
- VFS: Mounted root (ext2 filesystem) readonly.
- Mounted devfs on /dev
-
-
-
-
- You're probably running a recent distribution on an old machine. I
- saw this with the RH7.1 filesystem running on a Pentium. The shared
- library loader, ld.so, was executing an instruction (cmove) which the
- Pentium didn't support. That instruction was apparently added later.
- If you run UML under the debugger, you'll see the hang caused by one
- instruction causing an infinite SIGILL stream.
-
-
- The fix is to boot UML on an older filesystem.
-
-
-
1\b13\b3.\b.3\b3.\b. A\bA v\bva\bar\bri\bie\bet\bty\by o\bof\bf p\bpa\ban\bni\bic\bcs\bs a\ban\bnd\bd h\bha\ban\bng\bgs\bs w\bwi\bit\bth\bh /\b/t\btm\bmp\bp o\bon\bn a\ba r\bre\bei\bis\bse\ber\brf\bfs\bs f\bfi\bil\ble\bes\bsy\bys\bs-\b-
t\bte\bem\bm
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff