From 00fc82f17cff9295387d516384ecdc443acb1b22 Mon Sep 17 00:00:00 2001 From: Bradley Morgan Date: Sat, 3 Oct 2026 18:57:38 +0000 Subject: tashaboot: arm64 bringup, semihosting payload loader consoles on the pl011 the dtb points at, walks the memory node and chosen, loads an arm64 kernel Image over semihosting and jumps to it with the documented register state. string functions, printf and libfdt are vendored from lk (lk2nd) and u-boot so the libc surface is the one those projects already proved. built and booted on qemu virt, payload exits clean through semihosting. --- arch/arm64/lib/semihosting.S | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) create mode 100644 arch/arm64/lib/semihosting.S (limited to 'arch/arm64/lib/semihosting.S') diff --git a/arch/arm64/lib/semihosting.S b/arch/arm64/lib/semihosting.S new file mode 100644 index 0000000..6e3fc31 --- /dev/null +++ b/arch/arm64/lib/semihosting.S @@ -0,0 +1,18 @@ +/* SPDX-License-Identifier: GPL-2.0+ */ +/* + * semihosting.S - the trap instruction itself. qemu answers this when + * it is started with -semihosting, and nothing happens without it, so + * every caller has to cope with the no-debugger case. + * + * Copyright (C) 2026 Bradley Morgan + */ + +#include + +.pushsection .text.smh_trap, "ax" +/* long smh_trap(unsigned int sysnum, void *addr); */ +ENTRY(smh_trap) + hlt #0xf000 + ret +ENDPROC(smh_trap) +.popsection -- cgit v1.2.3