From 5143239e2bcc41f6aba8a56b73810f2f9965feb4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Alex=20R=C3=B8nne=20Petersen?= <alex@alexrp.com>
Date: Tue, 26 May 2026 08:08:53 +0200
Subject: [PATCH] std.start: add xtensa support

---
 lib/std/start.zig | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/lib/std/start.zig b/lib/std/start.zig
index 9491ef2045..e05208731e 100644
--- a/lib/std/start.zig
+++ b/lib/std/start.zig
@@ -183,6 +183,7 @@ fn _start() callconv(.naked) noreturn {
             .sparc, .sparc64 => ".cfi_undefined %%i7",
             .x86 => ".cfi_undefined %%eip",
             .x86_64 => ".cfi_undefined %%rip",
+            .xtensa, .xtensaeb => "", // No CFI support.
             else => @compileError("unsupported arch"),
         });
 
@@ -486,6 +487,15 @@ fn _start() callconv(.naked) noreturn {
             \\ sub %%sp, 2047, %%sp
             \\ ba,a %[posixCallMainAndExit]
             ,
+            .xtensa, .xtensaeb =>
+            // a0 = LR, a7 = FP, a1 = SP
+            \\ movi a0, 0
+            \\ movi a7, 0
+            \\ mov a2, sp
+            \\ movi a8, -16
+            \\ and sp, sp, a8
+            \\ callx0 %[posixCallMainAndExit]
+            ,
             else => @compileError("unsupported arch"),
         }
         :