Linking and linker relaxation fixes (#200)

bsp/espressif/esp/src/cpus/espressif-riscv.zig

@@ -67,7 +67,12 @@ pub const startup_logic = struct {
             :
             : [eos] "r" (@as(u32, microzig.config.end_of_stack)),
         );
-        asm volatile ("la gp, __global_pointer$");
+        asm volatile (
+            \\.option push
+            \\.option norelax
+            \\la gp, __global_pointer$
+            \\.option pop
+        );
         microzig.cpu.setStatusBit(.mtvec, microzig.config.end_of_stack);
         root.initialize_system_memories();
         microzig_main();

build/src/generate_linkerscript.zig

@@ -121,8 +121,9 @@ pub fn main() !void {
             \\  .data :
             \\  {
             \\     microzig_data_start = .;
-            \\     *(.rodata*)
+            \\     *(.sdata*)
             \\     *(.data*)
+            \\     *(.rodata*)
             \\     microzig_data_end = .;
             \\  } > ram0 AT> flash0
             \\
@@ -137,6 +138,14 @@ pub fn main() !void {
             \\
         );
     }
+
+    switch (program_args.cpu_arch) {
+        .riscv32, .riscv64 => try writer.writeAll(
+            \\  PROVIDE(__global_pointer$ = microzig_data_start + 0x800);
+        ),
+        else => {},
+    }
+
     try writer.writeAll("}\n");
 
     // TODO: Assert that the flash can actually hold all data!