Re: LOWRAM mmap: Invalid argument

["Bart Oldeman" <bartoldeman@users.sourceforge.net>]

Hi,

you can check the value of
/proc/sys/vm/mmap_min_addr
and if it is non-zero, use
echo 0 > /proc/sys/vm/mmap_min_addr

I am not sure what Ubuntu has been up to exactly: this is something
that only works with SELinux enabled in enforcing mode.

This is the help:
+config SECURITY_DEFAULT_MMAP_MIN_ADDR
+        int "Low address space to protect from user allocation"
+        depends on SECURITY
+        default 0
+        help
+         This is the portion of low virtual memory which should be protected
+         from userspace allocation.  Keeping a user from writing to low pages
+         can help reduce the impact of kernel NULL pointer bugs.
+
+         For most users with lots of address space a value of 65536 is
+         reasonable and should cause no problems.  Programs which use vm86
+         functionality would either need additional permissions from either
+         the LSM or the capabilities module or have this protection disabled.
+
+         This value can be changed after boot using the
+         /proc/sys/vm/mmap_min_addr tunable.
+
+

I am not sure how to give DOSEMU special permission -- maybe you could
ask Ubuntu kernel maintainers about why they changed mmap_min_addr?

(o and this is speculation on my part, perhaps there is a different
problem in which case I don't know).

Bart