From 889c5c4c7a32be298aa499a246dbfd0c5fea8a74 Mon Sep 17 00:00:00 2001 From: Aditya Gupta Date: Tue, 20 Aug 2024 16:00:03 +0530 Subject: hw/ppc: Implement -dtb support for PowerNV Currently any device tree passed with -dtb option in QEMU, was ignored by the PowerNV code. Read and pass the passed -dtb to the kernel, thus enabling easier debugging with custom DTBs. The existing behaviour when -dtb is 'not' passed, is preserved as-is. But when a '-dtb' is passed, it completely overrides any dtb nodes or changes QEMU might have done, such as '-append' arguments to the kernel (which are mentioned in /chosen/bootargs in the dtb), hence add warning when -dtb is being used Reviewed-by: Nicholas Piggin Signed-off-by: Aditya Gupta Signed-off-by: Nicholas Piggin --- hw/ppc/pnv.c | 51 ++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 40 insertions(+), 11 deletions(-) diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c index 795acc289f..f0f0d7567d 100644 --- a/hw/ppc/pnv.c +++ b/hw/ppc/pnv.c @@ -736,21 +736,27 @@ static void pnv_reset(MachineState *machine, ResetType type) } } - fdt = pnv_dt_create(machine); - - /* Pack resulting tree */ - _FDT((fdt_pack(fdt))); + if (machine->fdt) { + fdt = machine->fdt; + } else { + fdt = pnv_dt_create(machine); + /* Pack resulting tree */ + _FDT((fdt_pack(fdt))); + } qemu_fdt_dumpdtb(fdt, fdt_totalsize(fdt)); cpu_physical_memory_write(PNV_FDT_ADDR, fdt, fdt_totalsize(fdt)); - /* - * Set machine->fdt for 'dumpdtb' QMP/HMP command. Free - * the existing machine->fdt to avoid leaking it during - * a reset. - */ - g_free(machine->fdt); - machine->fdt = fdt; + /* Update machine->fdt with latest fdt */ + if (machine->fdt != fdt) { + /* + * Set machine->fdt for 'dumpdtb' QMP/HMP command. Free + * the existing machine->fdt to avoid leaking it during + * a reset. + */ + g_free(machine->fdt); + machine->fdt = fdt; + } } static ISABus *pnv_chip_power8_isa_create(PnvChip *chip, Error **errp) @@ -952,6 +958,14 @@ static void pnv_init(MachineState *machine) g_free(sz); exit(EXIT_FAILURE); } + + /* checks for invalid option combinations */ + if (machine->dtb && (strlen(machine->kernel_cmdline) != 0)) { + error_report("-append and -dtb cannot be used together, as passed" + " command line is ignored in case of custom dtb"); + exit(EXIT_FAILURE); + } + memory_region_add_subregion(get_system_memory(), 0, machine->ram); /* @@ -1003,6 +1017,21 @@ static void pnv_init(MachineState *machine) } } + /* load dtb if passed */ + if (machine->dtb) { + int fdt_size; + + warn_report("with manually passed dtb, some options like '-append'" + " will get ignored and the dtb passed will be used as-is"); + + /* read the file 'machine->dtb', and load it into 'fdt' buffer */ + machine->fdt = load_device_tree(machine->dtb, &fdt_size); + if (!machine->fdt) { + error_report("Could not load dtb '%s'", machine->dtb); + exit(1); + } + } + /* MSIs are supported on this platform */ msi_nonbroken = true; -- cgit v1.2.3