reset: Add RESET_TYPE_WAKEUP

Some devices need to distinguish cold start reset from waking up from a
suspended state. This patch adds new value to the enum, and updates the
i386 wakeup method to use this new reset type.

Message-ID: <20240904103722.946194-3-jmarcin@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>

1 files changed, 11 insertions, 1 deletions

diff --git a/docs/devel/reset.rst b/docs/devel/reset.rst
index ed41e09f16..74c7c0171a 100644
--- a/docs/devel/reset.rst
+++ b/docs/devel/reset.rst
@@ -44,6 +44,17 @@ The Resettable interface handles reset types with an enum ``ResetType``:
   value on each cold reset, such as RNG seed information, and which they
   must not reinitialize on a snapshot-load reset.
 
+``RESET_TYPE_WAKEUP``
+  If the machine supports waking up from a suspended state and needs to reset
+  its devices during wake-up (from the ``MachineClass::wakeup()`` method), this
+  reset type should be used for such a request. Devices can utilize this reset
+  type to differentiate the reset requested during machine wake-up from other
+  reset requests. For example, RAM content must not be lost during wake-up, and
+  memory devices like virtio-mem that provide additional RAM must not reset
+  such state during wake-ups, but might do so during cold resets. However, this
+  reset type should not be used for wake-up detection, as not every machine
+  type issues a device reset request during wake-up.
+
 ``RESET_TYPE_S390_CPU_NORMAL``
   This is only used for S390 CPU objects; it clears interrupts, stops
   processing, and clears the TLB, but does not touch register contents.
@@ -53,7 +64,6 @@ The Resettable interface handles reset types with an enum ``ResetType``:
   ``RESET_TYPE_S390_CPU_NORMAL`` does and also clears the PSW, prefix,
   FPC, timer and control registers. It does not touch gprs, fprs or acrs.
 
-
 Devices which implement reset methods must treat any unknown ``ResetType``
 as equivalent to ``RESET_TYPE_COLD``; this will reduce the amount of
 existing code we need to change if we add more types in future.