# HG changeset patch
# User stekloff@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
# Node ID 61acbc181fe4caff86a4a3ec4ba69ed43492b511
# Parent  72f9c751d3ea1f17ff513cd7fc2cbe671a9af7c9

To help the small memory issue, I've added a warning to xm for creating - 
"xm create" - a domain and setting - "xm mem-set" - a domain's memory with
less than 32 MBs. I've added a "--force-mem" option to force creating and 
setting memory below that mark. I've also patched the man page and the
user manual.

Signed-off-by: Daniel Stekloff <dsteklof@xxxxxxxxxx>

diff -r 72f9c751d3ea -r 61acbc181fe4 docs/man/xm.pod.1
--- a/docs/man/xm.pod.1	Wed Apr 19 17:32:20 2006
+++ b/docs/man/xm.pod.1	Fri Apr 21 14:45:12 2006
@@ -63,7 +63,7 @@
 so running curses based interfaces over the console B<is not
 advised>.  Vi tends to get very odd when using it over this interface.
 
-=item B<create> I<[-c]> I<configfile> I<[name=value]>..
+=item B<create> I<[-c]> I<configfile> I<[--force-mem]> I<[name=value]>..
 
 The create sub command requires a configfile and can optional take a
 series of name value pairs that add to or override variables defined
@@ -78,6 +78,12 @@
 not> mean the guest OS in the domain has actually booted, or is
 available for input.
 
+B<Warning>: Creating a domain with insufficient memory may cause out
+of memory errors. The domain needs enough memory to boot kernel and
+modules. Allocating less than 32MBs is not recommended. Use the
+I<--force-mem> option to create a domain with less than 32 MBs of
+memory.
+
 B<OPTIONS>
 
 =over 4 
@@ -86,6 +92,10 @@
 
 Attache console to the domain as soon as it has started.  This is
 useful for determining issues with crashing domains.
+
+=item B<--force-mem>
+
+Force domain creation with less than 32MBs of memory.
 
 =back
 
@@ -234,7 +244,7 @@
 The mem-max value may not correspond to the actual memory used in the
 Domain, as it may balloon down it's memory to give more back to the OS.
 
-=item B<mem-set> I<domain-id> I<mem>
+=item B<mem-set> I<domain-id> I<mem> I<[--force-mem]>
 
 Set the domain's used memory using the balloon driver.  Because this
 operation requires cooperation from the domain operating system, there
@@ -242,7 +252,9 @@
 
 B<Warning:> there is no good way to know in advance how small of a
 mem-set will make a domain unstable and cause it to crash.  Be very
-careful when using this command on running domains.
+careful when using this command on running domains. Setting a domain
+to less than 32 MBs isn't recommended. Use the I<--force-mem> option
+to set a domain to less than 32 MBs of memory.
 
 =item B<migrate> I<domain-id> I<host> I<[options]>
 
diff -r 72f9c751d3ea -r 61acbc181fe4 docs/src/user.tex
--- a/docs/src/user.tex	Wed Apr 19 17:32:20 2006
+++ b/docs/src/user.tex	Fri Apr 21 14:45:12 2006
@@ -837,7 +837,10 @@
 \item[kernel] Set this to the path of the kernel you compiled for use
   with Xen (e.g.\ \path{kernel = ``/boot/vmlinuz-2.6-xenU''})
 \item[memory] Set this to the size of the domain's memory in megabytes
-  (e.g.\ \path{memory = 64})
+  (e.g.\ \path{memory = 64}) {\bf WARNING}: Creating a domain with
+  insufficient memory may cause out of memory errors. The domain
+  needs enough memory to boot kernel and modules. Allocating less
+  than 32MBs is not recommended.
 \item[disk] Set the first entry in this list to calculate the offset
   of the domain's root partition, based on the domain ID\@.  Set the
   second to the location of \path{/usr} if you are sharing it between
@@ -1161,6 +1164,10 @@
 \path{xmexample2} file, which uses Python code to handle the
 \path{vmid} variable.
 
+{\bf WARNING}: Creating or setting a domain with insufficient memory
+may cause out of memory errors. The domain needs enough memory to
+boot kernel and modules. Allocating less than 32MBs is not
+recommended.
 
 %\part{Advanced Topics}
 
diff -r 72f9c751d3ea -r 61acbc181fe4 tools/python/xen/xm/create.py
--- a/tools/python/xen/xm/create.py	Wed Apr 19 17:32:20 2006
+++ b/tools/python/xen/xm/create.py	Fri Apr 21 14:45:12 2006
@@ -103,6 +103,10 @@
 gopts.opt('console_autoconnect', short='c',
           fn=set_true, default=0,
           use="Connect to the console after the domain is created.")
+
+gopts.opt('force-mem', short='m',
+          fn=set_true, default=0,
+          use="""Force memory creation even if under recommended 32 MB lower limit.""")
 
 gopts.var('vncviewer', val='no|yes',
           fn=set_bool, default=None,
@@ -774,6 +778,20 @@
         vnc_host = get_host_addr()
         vnc = 'VNC_VIEWER=%s:%d' % (vnc_host, vnc_port)
         vals.extra = vnc + ' ' + vals.extra
+
+def preprocess_memory(vals):
+    """Check if memory is set to less than 32 MBs, which is not
+    recommended. If so, warn and exit if force-mem option isn't set."""
+
+    if int(vals.memory) < 32 and not gopts.getopt("force-mem"):
+
+        warn(
+"""Creating a domain with insufficient memory may cause 
+out of memory errors. The domain needs enough memory to boot kernel 
+and modules. Allocating less than 32MBs is not recommended. Use 
+the \'--force-mem\' option to set memory below 32MBs.\n""")
+
+        sys.exit(1)
     
 def preprocess(vals):
     if not vals.kernel and not vals.bootloader:
@@ -785,6 +803,7 @@
     preprocess_nfs(vals)
     preprocess_vnc(vals)
     preprocess_vtpm(vals)
+    preprocess_memory(vals)
 
 
 def comma_sep_kv_to_dict(c):
diff -r 72f9c751d3ea -r 61acbc181fe4 tools/python/xen/xm/main.py
--- a/tools/python/xen/xm/main.py	Wed Apr 19 17:32:20 2006
+++ b/tools/python/xen/xm/main.py	Fri Apr 21 14:45:12 2006
@@ -50,13 +50,14 @@
 
 # Strings for shorthelp
 console_help = "console <DomId>                  Attach to domain DomId's console."
-create_help =  """create [-c] <ConfigFile>
+create_help =  """create [-c] <ConfigFile> [--force-mem]
                [Name=Value]..       Create a domain based on Config File"""
 destroy_help = "destroy <DomId>                  Terminate a domain immediately"
 help_help =    "help                             Display this message"
 list_help =    "list [--long] [DomId, ...]       List information about domains"
 mem_max_help = "mem-max <DomId> <Mem>            Set maximum memory reservation for a domain"
-mem_set_help = "mem-set <DomId> <Mem>            Adjust the current memory usage for a domain"
+mem_set_help = """mem-set <DomId> <Mem> [--force-mem]
+                                    Adjust the current memory usage for a domain"""
 migrate_help = "migrate <DomId> <Host>           Migrate a domain to another machine"
 pause_help =   "pause <DomId>                    Pause execution of a domain"
 reboot_help =  "reboot <DomId> [-w][-a]          Reboot a domain"
@@ -566,10 +567,18 @@
     server.xend.domain.maxmem_set(dom, mem)
     
 def xm_mem_set(args):
-    arg_check(args, "mem-set", 2)
+    arg_check(args, "mem-set", 2, 3)
+    alen = len(args)
 
     dom = args[0]
     mem_target = int_unit(args[1], 'm')
+    if mem_target < 32 and (alen < 3 or (alen > 2 and args[2] != '--force-mem')):
+        print """
+Warning: Setting a domain with insufficient memory may cause out of
+         memory errors. Allocating less than 32MBs is not recommended.
+         Use the \'--force-mem\' option to set below 32MBs
+        """
+        usage("mem-set")
 
     server.xend.domain.setMemoryTarget(dom, mem_target)