diff options
Diffstat (limited to 'roms/skiboot/test/hello_world/hello_kernel')
| -rw-r--r-- | roms/skiboot/test/hello_world/hello_kernel/hello_kernel.S | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/roms/skiboot/test/hello_world/hello_kernel/hello_kernel.S b/roms/skiboot/test/hello_world/hello_kernel/hello_kernel.S new file mode 100644 index 000000000..4f774c179 --- /dev/null +++ b/roms/skiboot/test/hello_world/hello_kernel/hello_kernel.S @@ -0,0 +1,48 @@ +// SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later +/* + * hello_kernel.S! + * + * Because skiboot has its own stack, we don't even need that! + * All we need to do is make an OPAL call to write to the console. + * + * Copyright 2014-2016 IBM Corp. + */ + + . = 0x0 + .globl _start +_start: +/* + * Save some values passed in from skiboot into registers that are + * non-volatile over OPAL calls. + * r8 is the OPAL base + * r9 is the OPAL entry point point + */ + mr %r13, %r8 + mr %r14, %r9 + + bl here +here: mflr %r8 /* work out where we are running */ + + li %r0, 1 /* OPAL_CONSOLE_WRITE */ + li %r3, 0 /* terminal 0 */ + addi %r4, %r8, len - here /* ptr to length of string */ + addi %r5, %r8, str - here /* ptr to string start */ + mr %r2, %r13 + mtctr %r14 + bctrl + + li %r0, 5 /* OPAL_CEC_POWER_DOWN */ + li %r3, 0 /* normal shutdown */ + mr %r2, %r13 + mtctr %r14 + bctrl + + /* We shouldn't get here but if we do, just wait here */ + b . + +len: + .long 0x00 + .long (strend - str) +str: + .string "Hello World!\n" +strend: |