virt-install: Warn if mem less than OS recommended

And if mem is abnormally low, like it appears user tried to specify
GiB not MiB

tests/clitest.py

@@ -795,7 +795,8 @@ c.add_invalid("--features smm=on --machine pc")  # smm=on doesn't work for machi
 
 c = vinst.add_category("nodisk-install", "--nographics --noautoconsole --nodisks")
 c.add_valid("--hvm --cdrom %(EXISTIMG1)s")  # Simple cdrom install
-c.add_valid("--os-variant winxp --cdrom %(EXISTIMG1)s")  # Windows (2 stage) install
+c.add_valid("--pxe --ram 16", grep="Requested memory 16 MiB is abnormally low")  # catch low memory error
+c.add_valid("--os-variant winxp --ram 32 --cdrom %(EXISTIMG1)s", grep="32 MiB is less than the recommended 64 MiB")  # Windows. Catch memory warning
 c.add_valid("--pxe --virt-type test")  # Explicit virt-type
 c.add_valid("--arch i686 --pxe")  # Explicitly fullvirt + arch
 c.add_valid("--location location=%(TREEDIR)s")  # Directory tree URL install

virt-install

@@ -339,6 +339,23 @@ def _show_nographics_warnings(options, guest, installer):
         return
 
 
+def _show_memory_warnings(guest):
+    if not guest.currentMemory:
+        return
+
+    res = guest.osinfo.get_recommended_resources()
+    rammb = guest.currentMemory // 1024
+    minram = (res.get_minimum_ram(guest.os.arch) or 0)
+    if minram:
+        if (minram // 1024) > guest.currentMemory:
+            logging.warning(_("Requested memory %s MiB is less than the "
+                "recommended %s MiB for OS %s"), rammb,
+                minram // (1024 * 1024), guest.osinfo.name)
+    elif rammb < 17:
+        logging.warning(_("Requested memory %s MiB is abnormally low. "
+            "Were you trying to specify GiB?"), rammb)
+
+
 def show_warnings(options, guest, installer, osdata):
     if options.pxe and not supports_pxe(guest):
         logging.warning(_("The guest's network configuration does not support "
@@ -353,6 +370,7 @@ def show_warnings(options, guest, installer, osdata):
         logging.warning(_("No operating system detected, VM performance may "
             "suffer. Specify an OS with --os-variant for optimal results."))
 
+    _show_memory_warnings(guest)
     _show_nographics_warnings(options, guest, installer)
 
 

virtinst/osdict.py

@@ -307,6 +307,11 @@ class _OsResources:
             if checkarch in resources and key in resources[checkarch]:
                 return resources[checkarch][key]
 
+    def _get_minimum_key(self, key, arch):
+        val = self._get_key(self._minimum, key, arch)
+        if val and val > 0:
+            return val
+
     def _get_recommended_key(self, key, arch):
         val = self._get_key(self._recommended, key, arch)
         if val and val > 0:
@@ -314,11 +319,16 @@ class _OsResources:
         # If we are looking for a recommended value, but the OS
         # DB only has minimum resources tracked, double the minimum
         # value as an approximation at a 'recommended' value
-        val = self._get_key(self._minimum, key, arch)
+        val = self._get_minimum_key(key, arch)
-        if val and val > 0:
+        if val:
+            logging.debug("No recommended value found for key='%s', "
+                    "using minimum=%s * 2", key, val)
             return val * 2
         return None
 
+    def get_minimum_ram(self, arch):
+        return self._get_minimum_key("ram", arch)
+
     def get_recommended_ram(self, arch):
         return self._get_recommended_key("ram", arch)