From 35027de4cf7e75f4b876fa1e515bf3cfad93d836 Mon Sep 17 00:00:00 2001
From: Thiago Jung Bauermann <thiago.bauermann@linaro.org>
Date: Sun, 27 Apr 2025 02:01:44 -0300
Subject: [PATCH] GDB: remote: Update tdesc parameters and packet size ...

... before using the g packet.
---
 gdb/regcache.c |  9 +++++++++
 gdb/regcache.h |  3 +++
 gdb/remote.c   | 19 +++++++++++++++++--
 3 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/gdb/regcache.c b/gdb/regcache.c
index eff4267fda8..120de8fd790 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -1408,6 +1408,15 @@ readable_regcache::update_tdesc_parameter (unsigned int param_id)
 
 /* See regcache.h.  */
 
+void
+readable_regcache::update_tdesc_parameters ()
+{
+  for (unsigned int i = 0; i < m_tdesc_parameter_status.size (); i++)
+    update_tdesc_parameter (i);
+}
+
+/* See regcache.h.  */
+
 register_status
 readable_regcache::tdesc_parameter_value (unsigned int param_id,
 					  gdb::array_view<gdb_byte> dst)
diff --git a/gdb/regcache.h b/gdb/regcache.h
index 7fa40e06e3c..8fc82d1913b 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -405,6 +405,9 @@ public:
   /* FIXME: Document.  */
   void update_tdesc_parameter (unsigned int param_id);
 
+  /* FIXME: Document.  */
+  void update_tdesc_parameters ();
+
   /* FIXME: Document.  */
   register_status tdesc_parameter_value (unsigned int param_id,
 					 gdb::array_view<gdb_byte> dst);
diff --git a/gdb/remote.c b/gdb/remote.c
index f51f9cf6985..8c6e8085941 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -8608,8 +8608,14 @@ remote_target::supply_expedited_registers (regcache *regcache,
     }
 
   if (regcache->has_variable_size_registers ())
-    rs->get_remote_arch_state (regcache->arch ())
-      ->update_packet_size (regcache, rs);
+    {
+      /* Presumably, the expedited registers allow recalculating the target
+	 description parameters.  */
+      regcache->update_tdesc_parameters ();
+
+      rs->get_remote_arch_state (regcache->arch ())
+	->update_packet_size (regcache, rs);
+    }
 }
 
 /* Called when it is decided that STOP_REPLY holds the info of the
@@ -9161,6 +9167,15 @@ remote_target::process_g_packet (struct regcache *regcache)
 void
 remote_target::fetch_registers_using_g (struct regcache *regcache)
 {
+  if (regcache->has_variable_size_registers ())
+    {
+      regcache->update_tdesc_parameters ();
+
+      remote_state *rs = get_remote_state ();
+      remote_arch_state *rsa = rs->get_remote_arch_state (regcache->arch ());
+      rsa->update_packet_size (regcache, rs);
+    }
+
   send_g_packet ();
   process_g_packet (regcache);
 }
-- 
2.47.2