@@ -68,6 +68,19 @@ configurations (e.g. -smp drawers=1,books=1,clusters=1 for x86 PC machine) is
marked deprecated since 9.0, users have to ensure that all the topology members
described with -smp are supported by the target machine.
+``-old-param`` option for booting Arm kernels via param_struct (since 10.0)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``-old-param`` command line option is specific to Arm targets:
+it is used when directly booting a guest kernel to pass it the
+command line and other information via the old ``param_struct`` ABI,
+rather than the newer ATAGS or DTB mechanisms. This option was only
+ever needed to support ancient kernels on some old board types
+like the ``akita`` or ``terrier``; it has been deprecated in the
+kernel since 2001. None of the board types QEMU supports need
+``param_struct`` support, so this option has been deprecated and will
+be removed in a future QEMU version.
+
User-mode emulator command line arguments
-----------------------------------------
@@ -3438,6 +3438,7 @@ void qemu_init(int argc, char **argv)
nb_prom_envs++;
break;
case QEMU_OPTION_old_param:
+ warn_report("-old-param is deprecated");
old_param = 1;
break;
case QEMU_OPTION_rtc:
The '-old-param' command line option is specific to Arm targets; it is very briefly documented as "old param mode". What this option actually does is change the behaviour when directly booting a guest kernel, so that command line arguments are passed to the kernel using the extremely old "param_struct" ABI, rather than the newer ATAGS or even newer DTB mechanisms. This support was added back in 2007 to support an old vendor kernel on the akita/terrier board types: https://mail.gnu.org/archive/html/qemu-devel/2007-07/msg00344.html Even then, it was an out-of-date mechanism from the kernel's point of view -- the kernel has had a comment since 2001 marking it as deprecated. As of mid-2024, the kernel only retained param_struct support for the RiscPC and Footbridge platforms: https://lore.kernel.org/linux-arm-kernel/2831c5a6-cfbf-4fe0-b51c-0396e5b0aeb7@app.fastmail.com/ None of the board types QEMU supports need param_struct support; mark this option as deprecated. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> --- docs/about/deprecated.rst | 13 +++++++++++++ system/vl.c | 1 + 2 files changed, 14 insertions(+)