diff --git a/src/arch/x86/bios/acpi.cc b/src/arch/x86/bios/acpi.cc
index 20cf088807..8cdcdac3f6 100644
--- a/src/arch/x86/bios/acpi.cc
+++ b/src/arch/x86/bios/acpi.cc
@@ -45,6 +45,20 @@
 #include "sim/byteswap.hh"
 #include "sim/sim_object.hh"
 
+Addr
+X86ISA::ACPI::LinearAllocator::alloc(std::size_t size, unsigned align)
+{
+    if (align) {
+        unsigned offset = next % align;
+        if (offset)
+            next += (align - offset);
+    }
+    Addr chunk = next;
+    next += size;
+    assert(0 == end || next <= end);
+    return chunk;
+}
+
 const char X86ISA::ACPI::RSDP::signature[] = "RSD PTR ";
 
 X86ISA::ACPI::RSDP::RSDP(const Params &p) : SimObject(p), oemID(p.oem_id),
diff --git a/src/arch/x86/bios/acpi.hh b/src/arch/x86/bios/acpi.hh
index bc6e2cd19e..6fe0f6e302 100644
--- a/src/arch/x86/bios/acpi.hh
+++ b/src/arch/x86/bios/acpi.hh
@@ -62,6 +62,24 @@ class RSDT;
 class XSDT;
 class SysDescTable;
 
+struct Allocator
+{
+    virtual Addr alloc(std::size_t size, unsigned align=1) = 0;
+};
+struct LinearAllocator : public Allocator
+{
+    LinearAllocator(Addr begin, Addr end=0) :
+        next(begin),
+        end(end)
+    {}
+
+    Addr alloc(std::size_t size, unsigned align) override;
+
+  protected:
+    Addr next;
+    Addr const end;
+};
+
 class RSDP : public SimObject
 {
   protected: