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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 <npiggin@gmail.com>
Signed-off-by: Aditya Gupta <adityag@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Aditya Gupta 2024-08-20 16:00:03 +05:30 committed by Nicholas Piggin
parent 6fb6f3096a
commit 889c5c4c7a
1 changed files with 40 additions and 11 deletions
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51
hw/ppc/pnv.c
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@ -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;