If you have problem to use subversion under redmine, but svn command itself works ok, the problem might be in incorrect home directory configured for user which is running redmine (can be apache user, fcgi user id…etc). Incorrect here means home directory points to a file instead of directory (ie. /dev/null) . One can reproduce this with setting HOME to point to file.
Example:
$ HOME=/dev/null svn --version
svn: Can't open file '/dev/null/.subversion/servers': Not a directory
$ HOME=/dev/null svn --version --quiet
svn: Can't open file '/dev/null/.subversion/servers': Not a directory
Solution is pretty simple, just change user home directory configuration (via usermod) or set somehow $HOME variable of the redmine execution environment to point to some directory (ie. HOME=/var/empty).
This misbehavior has been reported as subversion defect.
If you get following compilation error while emerging xen (resp. xen-tools):
arch/i386/core/cpu.c: In function 'get_cpuinfo':
arch/i386/include/bits/cpu.h:79:2: error: can't find a register in class 'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79:2: error: can't find a register in class 'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79:2: error: can't find a register in class 'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79:2: error: can't find a register in class 'BREG' while reloading 'asm'
arch/i386/include/bits/cpu.h:79:2: error: 'asm' operand has impossible constraints
arch/i386/include/bits/cpu.h:79:2: error: 'asm' operand has impossible constraints
arch/i386/include/bits/cpu.h:79:2: error: 'asm' operand has impossible constraints
arch/i386/include/bits/cpu.h:79:2: error: 'asm' operand has impossible constraints
make[7]: *** [bin/cpu.o] Error 1
make[7]: *** Waiting for unfinished jobs....
Than you should not only switch to non-hardened gentoo profile as everywhere is written (via eselect profile), but you need also to switch to vanilla gcc compilator (via gcc-config). Doing just one thing is not enough – thats the magic. You can switch back your profile & gcc back when xen compiled.