Kernel: Drop 32 bit userspace stack to 4 MiB

32 bit userspace only has 256 MiB reserved for stacks, so with 32 MiB
stacks it only allowed total of 7 threads. Now we can have up to 62
threads

kernel/include/kernel/Thread.h

@@ -38,8 +38,12 @@ namespace Kernel
 		//        stack overflows on some machines with 8 page stack
 		static constexpr size_t kernel_stack_size    { PAGE_SIZE * 16 };
 
-		// TODO: userspace stack is hard limited to 32 MiB, maybe make this dynamic?
+		// TODO: userspace stack size is hard limited, maybe make this dynamic?
+#if ARCH(x86_64)
 		static constexpr size_t userspace_stack_size { 32 << 20 };
+#elif ARCH(i686)
+		static constexpr size_t userspace_stack_size { 4 << 20 };
+#endif
 
 	public:
 		static BAN::ErrorOr<Thread*> create_kernel(entry_t, void*);