Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 97 insertions, 0 deletions

diff --git a/target/avr/gdbstub.c b/target/avr/gdbstub.c
new file mode 100644
index 000000000..1c1b908c9
--- /dev/null
+++ b/target/avr/gdbstub.c
@@ -0,0 +1,97 @@
+/*
+ * QEMU AVR gdbstub
+ *
+ * Copyright (c) 2016-2020 Michael Rolnik
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, see
+ * <http://www.gnu.org/licenses/lgpl-2.1.html>
+ */
+
+#include "qemu/osdep.h"
+#include "exec/gdbstub.h"
+
+int avr_cpu_gdb_read_register(CPUState *cs, GByteArray *mem_buf, int n)
+{
+    AVRCPU *cpu = AVR_CPU(cs);
+    CPUAVRState *env = &cpu->env;
+
+    /*  R */
+    if (n < 32) {
+        return gdb_get_reg8(mem_buf, env->r[n]);
+    }
+
+    /*  SREG */
+    if (n == 32) {
+        uint8_t sreg = cpu_get_sreg(env);
+
+        return gdb_get_reg8(mem_buf, sreg);
+    }
+
+    /*  SP */
+    if (n == 33) {
+        return gdb_get_reg16(mem_buf, env->sp & 0x0000ffff);
+    }
+
+    /*  PC */
+    if (n == 34) {
+        return gdb_get_reg32(mem_buf, env->pc_w * 2);
+    }
+
+    return 0;
+}
+
+int avr_cpu_gdb_write_register(CPUState *cs, uint8_t *mem_buf, int n)
+{
+    AVRCPU *cpu = AVR_CPU(cs);
+    CPUAVRState *env = &cpu->env;
+
+    /*  R */
+    if (n < 32) {
+        env->r[n] = *mem_buf;
+        return 1;
+    }
+
+    /*  SREG */
+    if (n == 32) {
+        cpu_set_sreg(env, *mem_buf);
+        return 1;
+    }
+
+    /*  SP */
+    if (n == 33) {
+        env->sp = lduw_p(mem_buf);
+        return 2;
+    }
+
+    /*  PC */
+    if (n == 34) {
+        env->pc_w = ldl_p(mem_buf) / 2;
+        return 4;
+    }
+
+    return 0;
+}
+
+vaddr avr_cpu_gdb_adjust_breakpoint(CPUState *cpu, vaddr addr)
+{
+    /*
+     * This is due to some strange GDB behavior
+     * Let's assume main has address 0x100:
+     * b main   - sets breakpoint at address 0x00000100 (code)
+     * b *0x100 - sets breakpoint at address 0x00800100 (data)
+     *
+     * Force all breakpoints into code space.
+     */
+    return addr % OFFSET_DATA;
+}