https://github.com/torvalds/linux
Revision 86d6f2bf61eb2a28fa63c0a19330d36226426477 authored by Renzo Davoli on 12 March 2009, 21:31:23 UTC, committed by Linus Torvalds on 12 March 2009, 23:20:23 UTC
It is currently impossible to run a user-mode linux machine inside another user-mode linux (UML on UML). It breaks after a few instructions. When it tries to check whether SYSEMU is installed (the inner) UML receives an inconsistent result (from the outer UML). This is the output of a broken attempt: $ ./linux mem=256m ubd0=cow Locating the bottom of the address space ... 0x0 Locating the top of the address space ... 0xc0000000 Core dump limits : soft - 0 hard - NONE Checking that ptrace can change system call numbers...OK Checking ptrace new tags for syscall emulation...unsupported Checking syscall emulation patch for ptrace...check_sysemu : expected SIGTRAP, got status = 256 $ The problem is the following: PTRACE_SYSCALL/SINGLESTEP is currently managed inside arch_ptrace for ARCH=um. PTRACE_SYSEMU/SUSEMU_SINGLESTEP is not captured in arch_ptrace's switch, therefore it is erroneously passed back to ptrace_request (in kernel/ptrace). This simple patch simply forces ptrace to return an error on PTRACE_SYSEMU/SUSEMU_SINGLESTEP as it is unsupported on ARCH=um, and fixes the problem. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Renzo Davoli <renzo@cs.unibo.it> Reviewed-by: WANG Cong <xiyou.wangcong@gmail.com> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent f1c7404
Tip revision: 86d6f2bf61eb2a28fa63c0a19330d36226426477 authored by Renzo Davoli on 12 March 2009, 21:31:23 UTC
UML on UML fixed: it did not start
UML on UML fixed: it did not start
Tip revision: 86d6f2b
File | Mode | Size |
---|---|---|
Documentation | ||
arch | ||
block | ||
crypto | ||
drivers | ||
firmware | ||
fs | ||
include | ||
init | ||
ipc | ||
kernel | ||
lib | ||
mm | ||
net | ||
samples | ||
scripts | ||
security | ||
sound | ||
usr | ||
virt | ||
.gitignore | -rw-r--r-- | 867 bytes |
.mailmap | -rw-r--r-- | 3.9 KB |
COPYING | -rw-r--r-- | 18.3 KB |
CREDITS | -rw-r--r-- | 91.3 KB |
Kbuild | -rw-r--r-- | 2.4 KB |
MAINTAINERS | -rw-r--r-- | 107.1 KB |
Makefile | -rw-r--r-- | 53.2 KB |
README | -rw-r--r-- | 16.7 KB |
REPORTING-BUGS | -rw-r--r-- | 3.1 KB |
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