diff --git a/lldb/include/lldb/Utility/RegisterValue.h b/lldb/include/lldb/Utility/RegisterValue.h
--- a/lldb/include/lldb/Utility/RegisterValue.h
+++ b/lldb/include/lldb/Utility/RegisterValue.h
@@ -26,7 +26,8 @@
 
 class RegisterValue {
 public:
-  enum { kMaxRegisterByteSize = 64u };
+  // big enough to support up to 256 byte AArch64 SVE
+  enum { kMaxRegisterByteSize = 256u };
 
   enum Type {
     eTypeInvalid,
@@ -261,7 +262,7 @@
   struct {
     uint8_t bytes[kMaxRegisterByteSize]; // This must be big enough to hold any
                                          // register for any supported target.
-    uint8_t length;
+    uint16_t length;
     lldb::ByteOrder byte_order;
   } buffer;
 };
diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp
@@ -2040,7 +2040,7 @@
         packet, "P packet missing '=' char after register number");
 
   // Parse out the value.
-  uint8_t reg_bytes[32]; // big enough to support up to 256 bit ymmN register
+  uint8_t reg_bytes[RegisterValue::kMaxRegisterByteSize];
   size_t reg_size = packet.GetHexBytesAvail(reg_bytes);
 
   // Get the thread to use.
diff --git a/lldb/source/Utility/RegisterValue.cpp b/lldb/source/Utility/RegisterValue.cpp
--- a/lldb/source/Utility/RegisterValue.cpp
+++ b/lldb/source/Utility/RegisterValue.cpp
@@ -810,7 +810,7 @@
       if (buffer.length != rhs.buffer.length)
         return false;
       else {
-        uint8_t length = buffer.length;
+        uint16_t length = buffer.length;
         if (length > kMaxRegisterByteSize)
           length = kMaxRegisterByteSize;
         return memcmp(buffer.bytes, rhs.buffer.bytes, length) == 0;