Currently tests are run with the --kernel option of Qemu, which will
load the ELF file and jump to the start address. When booting from
disk, we need to specify a start address. This is done by setting the
initial short PSW at 0x0.
.text was moved to 0x11000 because the bootloader can write from
0x10480 until 0x11000 if it has a lot to write. 0x10480 to 0x10600 was
not enough safe space.
Signed-off-by: Janosch Frank <frankja@xxxxxxxxxxxxx>
Reviewed-by: Thomas Huth <thuth@xxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
---
s390x/cstart64.S | 8 +++++++-
s390x/flat.lds | 13 ++++++++++++-
2 files changed, 19 insertions(+), 2 deletions(-)
diff --git a/s390x/cstart64.S b/s390x/cstart64.S
index dc7ddd6..385915e 100644
--- a/s390x/cstart64.S
+++ b/s390x/cstart64.S
@@ -14,7 +14,13 @@
.section .init
-/* entry point - for KVM + TCG we directly start in 64 bit mode */
+/*
+ * Short init between 0x10000 and 0x10480 and then jump to 0x11000.
+ * 0x10480 - 0x11000 are written to by bootloader.
+ *
+ * For KVM and TCG kernel boot we are in 64 bit z/Arch mode.
+ * When booting from disk the initial short psw is in 31 bit mode.
+ */
.globl start
start:
/* setup stack */
diff --git a/s390x/flat.lds b/s390x/flat.lds
index b6e2172..977af7c 100644
--- a/s390x/flat.lds
+++ b/s390x/flat.lds
@@ -1,10 +1,21 @@
SECTIONS
{
+ /*
+ * Initial short psw for disk boot, with 31 bit addressing for
+ * non z/Arch environment compatibility and the instruction
+ * address 0x10000 (cstart64.S .init).
+ */
+ .lowcore : {
+ . = 0;
+ LONG(0x00080000)
+ LONG(0x80010000)
+ }
+ . = 0x10000;
.text : {
*(.init)
. = 0x480;
ipl_args = .;
- . = 0x600;
+ . = 0x1000;
*(.text)
*(.text.*)
}
--
2.14.3
