diff --git a/except.hpp b/except.hpp
index a66a3c3..604cdb3 100644
--- a/except.hpp
+++ b/except.hpp
@@ -49,10 +49,18 @@ namespace cruft::vk {
             >;
 
             if constexpr (returns_vkresult) {
-                try_code (func (maybe_native (args)...));
+                try_code (
+                    std::invoke (
+                        std::forward<FuncT> (func),
+                        maybe_native (std::forward<Args> (args))...
+                    )
+                );
                 return;
             } else {
-                return func (maybe_native (args)...);
+                return std::invoke (
+                    std::forward<FuncT> (func),
+                    maybe_native (std::forward<Args> (args))...
+                );
             }
         }
 
@@ -117,7 +125,9 @@ namespace cruft::vk {
         }
 
 
-        //---------------------------------------------------------------------
+        ///--------------------------------------------------------------------
+        /// Safely calls a function that returns an array of Handle objects,
+        /// and returns a vector of wrapped objects.
         template <
             typename ReturnT,
             template <typename,typename...> class ContainerT = std::vector,
diff --git a/icd/vendor.cpp b/icd/vendor.cpp
index 6a3d9c7..6c57dae 100644
--- a/icd/vendor.cpp
+++ b/icd/vendor.cpp
@@ -1,49 +1,81 @@
-#include "vendor.hpp"
-
-#include <cruft/json/tree.hpp>
-
-using cruft::vk::icd::vendor;
-
-
-///////////////////////////////////////////////////////////////////////////////
-template <>
-cruft::vk::icd::icd_t
-json::tree::io<cruft::vk::icd::icd_t>::deserialise (json::tree::node const &obj)
-{
-    return {
-        .file_format_version = obj["file_format_version"].as_string (),
-        .icd = {
-            .library_path = obj["ICD"]["library_path"].as_string ().native (),
-            .api_version = obj["ICD"]["api_version"].as_string (),
-        },
-    };
-}
-
-
-///////////////////////////////////////////////////////////////////////////////
-cruft::vk::icd::global_table const *cruft::vk::icd::g_table;
-
-
-
-///////////////////////////////////////////////////////////////////////////////
-vendor::vendor (icd_t const &_icd):
-    vendor (cruft::library (_icd.icd.library_path))
-{ ; }
-
-
-//-----------------------------------------------------------------------------
-vendor::vendor (::cruft::library &&_library)
-    : m_library (std::move (_library))
-    , m_get_proc (
-        m_library.symbol<decltype(m_get_proc)> ("vk_icdGetInstanceProcAddr")
-    )
-{
-    #define LOADFN(name)            \
-    vtable.name = reinterpret_cast< \
-        decltype(vtable.name)       \
-    > (                             \
-        m_get_proc(nullptr, #name)  \
-    );
-
-    MAP_INSTANCE_COMMANDS (LOADFN)
+#include "vendor.hpp"
+
+#include <cruft/json/tree.hpp>
+
+#include <cruft/util/std.hpp>
+#include <cruft/util/log.hpp>
+
+using cruft::vk::icd::vendor;
+
+
+#define MAP_ICD_COMMANDS(FUNC,...) MAP0(FUNC,\
+    vk_icdNegotiateLoaderICDInterfaceVersion,\
+    vk_icdGetInstanceProcAddr,\
+    vk_icdGetPhysicalDeviceProcAddr)
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <>
+cruft::vk::icd::icd_t
+json::tree::io<cruft::vk::icd::icd_t>::deserialise (json::tree::node const &obj)
+{
+    return {
+        .file_format_version = obj["file_format_version"].as_string (),
+        .icd = {
+            .library_path = obj["ICD"]["library_path"].as_string ().native (),
+            .api_version = obj["ICD"]["api_version"].as_string (),
+        },
+    };
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+vendor::vendor (icd_t const &_icd):
+    vendor (cruft::library (_icd.icd.library_path))
+{ ; }
+
+
+//-----------------------------------------------------------------------------
+vendor::vendor (::cruft::library &&_library)
+  : m_library (std::move (_library))
+{
+    // Negotiate needs to be called before anything else. But we load all the
+    // ICD calls at once for simplicity.
+    #define GET(NAME) vtable.NAME = m_library.symbol<decltype(vtable.NAME)> (#NAME);
+    MAP_ICD_COMMANDS (GET)
+    #undef GET
+
+    version = 2;
+    switch (auto err = vtable.vk_icdNegotiateLoaderICDInterfaceVersion (&version); err) {
+    case VK_ERROR_INCOMPATIBLE_DRIVER:
+        static constexpr char incompatible_message[] = "Incompatible Vulkan ICD interface";
+        LOG_ERROR ("%! %!", incompatible_message, version);
+        throw std::runtime_error (incompatible_message);
+
+    default:
+        static constexpr char unknown_message[] = "Unknown Vulkan ICD interface response";
+        LOG_ERROR (
+            "%! %!",
+            unknown_message,
+            static_cast<std::underlying_type_t<decltype(err)>>(err)
+        );
+
+        throw std::runtime_error (unknown_message);
+
+    case VK_SUCCESS:
+        LOG_INFO ("vk::icd version %!", version);
+        break;
+    }
+
+    // Only load the instance table after we've queried all the icd functions.
+    itable = {
+        #define LOADFN(NAME)        \
+        .NAME = reinterpret_cast<   \
+            decltype(itable.NAME)   \
+        > (                         \
+            vtable.vk_icdGetInstanceProcAddr (nullptr, #NAME)  \
+        ),
+
+        MAP_INSTANCE_COMMANDS (LOADFN)
+    };
 }
\ No newline at end of file
diff --git a/icd/vendor.hpp b/icd/vendor.hpp
index 1fc7c77..0e76883 100644
--- a/icd/vendor.hpp
+++ b/icd/vendor.hpp
@@ -4,6 +4,7 @@
 #include <cruft/vk/icd/vtable.hpp>
 
 #include <cruft/util/library.hpp>
+#include <cruft/util/std.hpp>
 
 #include <string>
 #include <filesystem>
@@ -24,6 +25,12 @@ namespace cruft::vk::icd {
     enumerate (void);
 
 
+    struct vendor_table {
+        VkResult (*vk_icdNegotiateLoaderICDInterfaceVersion)(u32*) = nullptr;
+        void* (*vk_icdGetInstanceProcAddr) (VkInstance, char const*) = nullptr;
+        void* (*vk_icdGetPhysicalDeviceProcAddr) (VkInstance, char const*) = nullptr;
+    };
+
     class vendor {
     public:
         vendor (icd_t const&);
@@ -33,9 +40,8 @@ namespace cruft::vk::icd {
         ::cruft::library m_library;
 
     public:
-        global_table vtable;
-
-        using get_proc_t = void* (*)(VkInstance, char const*);
-        get_proc_t const m_get_proc;
+        vendor_table vtable;
+        instance_table itable;
+        u32 version = 0;
     };
 }
diff --git a/icd/vendor_posix.cpp b/icd/vendor_posix.cpp
index 3f3b945..d99135c 100644
--- a/icd/vendor_posix.cpp
+++ b/icd/vendor_posix.cpp
@@ -41,6 +41,9 @@ cruft::vk::icd::enumerate (void)
         for (size_t i = 0; i < words.we_wordc; ++i) {
             try {
                 for (auto const &path: fs::directory_iterator (words.we_wordv[i])) {
+                    if (path.is_directory ())
+                        continue;
+
                     found.push_back (from_json<icd_t> (*json::tree::parse (path)));
                 }
             } catch (std::exception const &e) {
diff --git a/icd/vtable.cpp b/icd/vtable.cpp
index 309b3a4..72f00a5 100644
--- a/icd/vtable.cpp
+++ b/icd/vtable.cpp
@@ -4,4 +4,5 @@ using cruft::vk::icd::instance_table;
 
 
 ///////////////////////////////////////////////////////////////////////////////
-
+cruft::vk::icd::vendor_table const *cruft::vk::icd::v_table = nullptr;
+cruft::vk::icd::instance_table const *cruft::vk::icd::i_table = nullptr;
diff --git a/object.hpp b/object.hpp
index 04c1fed..cd09e44 100644
--- a/object.hpp
+++ b/object.hpp
@@ -90,16 +90,18 @@ namespace cruft::vk {
 
 
     ///////////////////////////////////////////////////////////////////////////
-    /// a vulkan object that is obtained by listings from a parent object.
+    /// A vulkan object that is obtained by listings from a parent object.
     template <typename SelfT, typename ParentT>
     struct enumerated : public object<SelfT> {
         using object<SelfT>::object;
 
+        /// Returns a vector of available objects given a parent object.
         static std::vector<SelfT>
         find (const ParentT &parent)
         {
             return error::try_handles<SelfT> (
-                enum_traits<native_t<SelfT>>::enumerate, parent.native ()
+                enum_traits<native_t<SelfT>>::enumerate,
+                parent.native ()
             );
         }
     };
diff --git a/tools/info.cpp b/tools/info.cpp
index fcade9a..7232657 100644
--- a/tools/info.cpp
+++ b/tools/info.cpp
@@ -30,7 +30,8 @@ main (int, char**)
     std::cout << "[ ";
     for (auto const &i: cruft::vk::icd::enumerate ()) {
         cruft::vk::icd::vendor v (i);
-        cruft::vk::icd::g_table = &v.vtable;
+        cruft::vk::icd::i_table = &v.itable;
+        cruft::vk::icd::v_table = &v.vtable;
 
         cruft::vk::instance instance;
 
diff --git a/tools/spec.py b/tools/spec.py
index 2e1954f..b201196 100644
--- a/tools/spec.py
+++ b/tools/spec.py
@@ -3,6 +3,7 @@
 import sys
 import logging
 from typing import List, Dict, Set, TextIO
+import pprint
 
 import xml.etree.ElementTree
 
@@ -392,32 +393,27 @@ class Constant(Type):
 class Command(Type):
     class Param(Type):
         name: str
-        """An appropriate title for this parameter"""
+        """An string that can be used to refer to the parameter variable"""
         type: str
         """The name of this parameter's dependant type"""
         param: str
         """
         The components of this type for a C definition (ie, includes
-        pointer, const, and other decorations
+        pointer, const, other decorations, _and_ the variable name (which must
+        be the same as self.name for a useful system).
         """
 
-        def __init__(self, node, **kwargs):
-            assert node.tag == 'param'
-
+        def __init__(self, name:str, type:str, param:str, depends:List[str]):
             super().__init__(
-                name=node.find('name').text,
-                depends=[node.find('type').text],
-                **kwargs
+                name=name,
+                depends=depends,
             )
 
-            self.type = node.find('type').text
+            self.type = type
+            self.param = param
 
-            self.param = ""
-            for i in node.iter():
-                self.param += i.text or ""
-                self.param += i.tail or ""
-            # normalise whitespace
-            self.param = " ".join(self.param.split())
+        def __repr__(self) -> str:
+            return f"{{ name: '{self.name}', type: '{self.type}', param: '{self.param}' }}"
 
         def is_pointer(self):
             return '*' in self.param
@@ -429,6 +425,9 @@ class Command(Type):
         self.params = params
         self.depends += depends or []
 
+    def __repr__(self) -> str:
+        return f"{{ name: '{self.name}', result: '{self.result}', param: {self.params} }}"
+
     def declare(self):
         return 'extern "C" %(result)s %(name)s (%(params)s) noexcept;' % {
             'name': rename(self.name),
@@ -436,14 +435,6 @@ class Command(Type):
             'params': ", ".join(p.param for p in self.params)
         }
 
-    def is_global(self, reg: Registry):
-        if not self.params:
-            return True
-
-        first_name = self.params[0].type
-        first_obj = reg.types[first_name]
-        return not isinstance(first_obj, Handle)
-
     def is_instance(self, reg: Registry):
         assert reg
 
@@ -454,11 +445,11 @@ class Command(Type):
         first_obj = reg.types[first_name]
 
         if not isinstance(first_obj, Handle):
-            return False
+            return True
 
-        instance = first_obj.has_parent('VkInstance', reg)
-        device = first_obj.has_parent('VkPhysicalDevice', reg)
-        return instance and not device
+        instance = first_obj.name == 'VkInstance'
+        physical = first_obj.name == 'VkPhysicalDevice'
+        return instance or physical
 
     def is_device(self, reg: Registry):
         if not self.params:
@@ -469,24 +460,18 @@ class Command(Type):
         if not isinstance(first_obj, Handle):
             return False
 
-        return first_obj.has_parent('VkPhysicalDevice', reg)
+        for i in ['VkDevice', 'VkQueue', 'VkCommandBuffer']:
+            if first_obj.has_parent(i, reg):
+                return True
+
+        return False
 
 
 ###############################################################################
 class Require(object):
-    def __init__(self, root):
-        self.values = []
-        self.depends = []
-
-        for node in root:
-            if node.tag == 'enum':
-                self.values.append(node)
-            elif node.tag in ['command', 'type']:
-                self.depends.append(node.attrib['name'])
-            elif node.tag in ['comment']:
-                pass
-            else:
-                raise RuntimeError("Unknown requires node")
+    def __init__(self, values, depends: List[str]):
+        self.values = values or []
+        self.depends = depends or []
 
     def apply(self, reg: Registry, extnumber=None):
         required = []
@@ -559,7 +544,7 @@ class Extension(Type):
 
         for node in root:
             if node.tag == 'require':
-                self.requires.append(Require(node))
+                self.requires.append(parse_require(node))
             else:
                 raise RuntimeError("Unknown extension node")
 
@@ -660,6 +645,28 @@ def parse_enums(reg: Registry, root):
         else:
             owner[valuename] = Constant(node)
 
+#------------------------------------------------------------------------------
+def parse_param(root) -> Command.Param:
+    assert root.tag == 'param'
+
+    param = ""
+    for i in root.iter():
+        param += i.text or ""
+        param += i.tail or ""
+    # normalise whitespace
+    param = " ".join(param.split())
+
+    name = root.find('name').text
+    type = root.find('type').text
+    depends = [root.find('type').text]
+
+    return Command.Param(
+        name=name,
+        type=type,
+        param=param,
+        depends=depends,
+    )
+
 
 # -----------------------------------------------------------------------------
 def parse_commands(reg: Registry, root):
@@ -677,7 +684,7 @@ def parse_commands(reg: Registry, root):
         name = proto.find('name').text
 
         result = proto.find('type').text
-        params = [Command.Param(p) for p in node.findall('./param')]
+        params = [parse_param(p) for p in node.findall('./param')]
         depends = [result]
         for p in params:
             depends += p.depends
@@ -686,6 +693,25 @@ def parse_commands(reg: Registry, root):
 
 
 # -----------------------------------------------------------------------------
+def parse_require(root) -> Require:
+    assert root.tag == 'require'
+
+    values = []
+    depends = []
+
+    for node in root:
+        if node.tag == 'enum':
+            values.append(node)
+        elif node.tag in ['command', 'type']:
+            depends.append(node.attrib['name'])
+        elif node.tag in ['comment']:
+            pass
+        else:
+            raise RuntimeError("Unknown requires node")
+
+    return Require(values=values, depends=depends)
+
+##-----------------------------------------------------------------------------
 def parse_feature(reg: Registry, root):
     assert root.tag == 'feature'
 
@@ -695,7 +721,7 @@ def parse_feature(reg: Registry, root):
     requires = []
     for node in root:
         if 'require' == node.tag:
-            requires.append(Require(node))
+            requires.append(parse_require(node))
         else:
             raise RuntimeError("Unhandled feature node")
 
@@ -769,7 +795,6 @@ def write_icd(dst: TextIO, q: List[Type], reg: Registry):
     commands = [i for i in q if isinstance(i, Command)]
 
     collections = {
-        'global': Command.is_global,
         'instance': Command.is_instance,
         'device': Command.is_device,
     }
@@ -789,9 +814,13 @@ def write_icd(dst: TextIO, q: List[Type], reg: Registry):
     """)
 
     for name, test in collections.items():
+        curr = [i for i in commands if     test(i, reg)]
+        next = [i for i in commands if not test(i, reg)]
+        commands = next
+
         dst.write(f"""
             #define MAP_{name.upper()}_COMMANDS(FUNC) \
-                MAP0(FUNC,{",".join(i.name for i in commands if i.is_global(reg))})
+                MAP0(FUNC,{",".join([i.name for i in curr])})
 
             struct {name}_table{{
         """)
@@ -799,7 +828,7 @@ def write_icd(dst: TextIO, q: List[Type], reg: Registry):
         # Generate the vtable entries for instance methods
         dst.writelines((
             f"{obj.result} (*{obj.name}) ({','.join(p.param for p in obj.params)}) = nullptr;"
-            for obj in commands if test(obj, reg)
+            for obj in curr
         ))
 
         dst.write("""
@@ -807,7 +836,9 @@ def write_icd(dst: TextIO, q: List[Type], reg: Registry):
         """)
 
     dst.write("""
-        extern cruft::vk::icd::global_table const *g_table [[maybe_unused]];
+        struct vendor_table;
+        extern cruft::vk::icd::vendor_table const *v_table;
+        extern cruft::vk::icd::instance_table const *i_table;
     }
     """)
 
@@ -823,30 +854,88 @@ def write_dispatch(dst: TextIO, q: List[Type], reg: Registry):
 
     #pragma GCC diagnostic ignored "-Wunused-parameter"
 
+    template <typename HandleT, typename TableT>
     struct indirect {
-        void *handle;
-        void const *table;
+        HandleT handle;
+        TableT table;
     };
     """)
 
+    implementations = {
+        'vkCreateInstance': """
+            auto res = std::make_unique<indirect<VkInstance,cruft::vk::icd::instance_table>> ();
+            auto err = cruft::vk::icd::i_table->vkCreateInstance (pCreateInfo, pAllocator, &res->handle);
+            if (err != VK_SUCCESS)
+                return err;
+            
+            #define GET(NAME) res->table.NAME = reinterpret_cast<decltype(&NAME)> (cruft::vk::icd::v_table->vk_icdGetInstanceProcAddr (res->handle, #NAME));
+            MAP_INSTANCE_COMMANDS(GET)
+            #undef GET
+            
+            #define GET(NAME) if (!res->table.NAME) res->table.NAME = reinterpret_cast<decltype(&NAME)> (res->table.vkGetInstanceProcAddr (res->handle, #NAME));
+            MAP_INSTANCE_COMMANDS(GET)
+            #undef GET
+            
+            *pInstance = (VkInstance)res.release (); 
+            return err;
+        """,
+
+        'vkCreateDevice': """
+            (void)physicalDevice;
+            (void)pCreateInfo;
+            (void)pAllocator;
+            (void)pDevice;
+            unimplemented (); 
+        """,
+
+        'vkEnumeratePhysicalDevices': """
+            auto const entry = reinterpret_cast<
+                indirect<VkInstance,cruft::vk::icd::instance_table> const*
+            > (instance);
+            
+            if (!pPhysicalDeviceCount || !pPhysicalDevices) {
+                return (entry->table.vkEnumeratePhysicalDevices)(
+                    entry->handle, pPhysicalDeviceCount, pPhysicalDevices
+                );
+            }
+            
+            std::vector<VkPhysicalDevice> res (*pPhysicalDeviceCount);
+            auto err = (entry->table.vkEnumeratePhysicalDevices)(
+                entry->handle, pPhysicalDeviceCount, res.data ()
+            );
+            res.resize (*pPhysicalDeviceCount);
+            
+            if (err != VK_SUCCESS)
+                return err;
+                
+            for (uint32_t i = 0; i < *pPhysicalDeviceCount; ++i) {
+                auto wrapped = std::make_unique<indirect<VkPhysicalDevice,cruft::vk::icd::instance_table>> ();
+                wrapped->handle = res[i];
+                
+                #define GET(NAME) wrapped->table.NAME = wrapped->table.NAME ?: reinterpret_cast<decltype(&NAME)> (vkGetInstanceProcAddr (instance, #NAME));
+                MAP_INSTANCE_COMMANDS(GET)
+                #undef GET
+                
+                pPhysicalDevices[i] = (VkPhysicalDevice)wrapped.release ();
+            }
+            
+            return err;
+        """
+    }
+
     for obj in (i for i in q if isinstance(i, Command)):
         first_arg = reg.types[obj.params[0].type]
 
-        if obj.is_global(reg):
-            dst.write(f"""
-            extern "C"
-            {obj.result}
-            {rename(obj.name)} ({", ".join(p.param for p in obj.params)}) noexcept {{
-                return cruft::vk::icd::g_table->{obj.name} ({", ".join(p.name for p in obj.params)});
-            }}
-            """)
-            continue
-        elif obj.is_instance(reg):
+        instance_forward = f"""
+            return cruft::vk::icd::i_table->{obj.name} ({", ".join(p.name for p in obj.params)});
+        """
+
+        if obj.is_instance(reg):
             table = 'instance'
         elif obj.is_device(reg):
             table = 'device'
         else:
-            raise Exception("Unhandled command type")
+            raise Exception(f"Unhandled command type for {obj}")
 
         if obj.params:
             last_param = obj.params[-1]
@@ -855,15 +944,20 @@ def write_dispatch(dst: TextIO, q: List[Type], reg: Registry):
         else:
             is_creating = False
 
+        if obj.is_instance(reg) and obj.params[0].type not in ['VkInstance', 'VkPhysicalDevice']:
+            forwarding = f"return ::cruft::vk::icd::i_table->{obj.name} ({', '.join (i.name for i in obj.params)});"
+        else:
+            forwarding = f"""
+                auto const entry = reinterpret_cast<indirect<{obj.params[0].type},cruft::vk::icd::{table}_table> const*> ({obj.params[0].name});
+
+                return (entry->table.{obj.name})(
+                    {", ".join(['entry->handle'] + [p.name for p in obj.params[1:]])}
+                );
+            """
+
         dst.write(f"""
         extern "C" {obj.result} {rename(obj.name)} ({", ".join(p.param for p in obj.params)}) noexcept {{
-            auto const  entry = reinterpret_cast<indirect const*> ({obj.params[0].name});
-            auto const *table = reinterpret_cast<cruft::vk::icd::{table}_table const*> (entry->table);
-
-            return (table->{obj.name})(
-                reinterpret_cast<decltype({obj.params[0].name})> (entry->handle)
-                {", ".join([''] + [p.name for p in obj.params[1:]])}
-            );
+            {implementations.get(obj.name, forwarding)}
         }}
         """)
 
@@ -912,6 +1006,53 @@ def main():
     reg.types['VK_DEFINE_HANDLE'] = AliasType("VK_DEFINE_HANDLE", "void*")
     reg.types['VK_NULL_HANDLE'] = AliasValue("VK_NULL_HANDLE", "nullptr")
 
+    #reg.types['vk_icdGetInstanceProcAddr'] = Command(
+    #    name='vk_icdGetInstanceProcAddr',
+    #    result='void*',
+    #    params=[
+    #        Command.Param(
+    #            name='instance',
+    #            type='VkInstance',
+    #            param='VkInstance instance',
+    #            depends=['VkInstance']
+    #        ),
+    #        Command.Param(
+    #            name='pName',
+    #            type='void*',
+    #            param='char const *pName',
+    #            depends=[]
+    #        ),
+    #    ]
+    #)
+    #reg.types['vk_icdGetPhysicalDeviceProcAddr'] = Command(
+    #    name='vk_icdGetPhysicalDeviceProcAddr',
+    #    result='void*',
+    #    params=[
+    #        Command.Param(
+    #            name='instance',
+    #            type='VkInstance',
+    #            param='VkInstance instance',
+    #            depends=['VkInstance']
+    #        ),
+    #        Command.Param(
+    #            name='pName',
+    #            type='void*',
+    #            param='char const *pName',
+    #            depends=[]
+    #        ),
+    #    ]
+    #)
+
+    #icd = Feature(
+    #    "__nerdcruft_icd",
+    #    requires=[
+    #        Require(None, ["vk_icdGetInstanceProcAddr"]),
+    #        Require(None, ["vk_icdGetPhysicalDeviceProcAddr"])
+    #    ]
+    #)
+    #reg.features['__nerdcruft_icd'] = icd
+    #reg.types['__nerdcruft_icd'] = reg.features['__nerdcruft_icd']
+
     # Request serialisation of all features
     #features = [Feature(n) for n in root.findall('./feature')]
     #features = dict((f.name,f) for f in features)