update for more ABIs supporting c-variadics
diff --git a/src/items/external-blocks.md b/src/items/external-blocks.md
index 0e04822..dbeb479 100644
--- a/src/items/external-blocks.md
+++ b/src/items/external-blocks.md
@@ -189,6 +189,17 @@
> [!WARNING]
> The `safe` qualifier should not be used on a function in an `extern` block unless that function guarantees that it will not access the variadic arguments at all. Passing an unexpected number of arguments or arguments of unexpected type to a variadic function may lead to [undefined behavior][undefined].
+r[items.extern.variadic.conventions]
+Variadic parameters can only be specified with `extern` blocks with the following ABI strings:
+- `"aapcs"`
+- `"C"`
+- `"cdecl"`
+- `"efiapi"`
+- `"sysv64"`
+- `"win64"`
+
+This also includes the corresponding [`-unwind` variants][items.fn.extern.unwind].
+
r[items.extern.attributes]
## Attributes on extern blocks
diff --git a/src/types/function-pointer.md b/src/types/function-pointer.md
index 03c8793..41ee203 100644
--- a/src/types/function-pointer.md
+++ b/src/types/function-pointer.md
@@ -50,10 +50,7 @@
function], and the `extern` qualifier indicates it is an [extern function].
r[type.fn-pointer.constraint-variadic]
-Variadic parameters can only be specified with [`extern`] function types with
-the `"C"` or `"cdecl"` calling convention.
-
-This also includes the corresponding [`-unwind` variants][items.fn.extern.unwind].
+For the function to be variadic, its `extern` ABI must be on the [list of ABIs that allow variadic calls][items.extern.variadic.conventions].
r[type.fn-pointer.attributes]
## Attributes on function pointer parameters
