hw/mips/boston: Support dumpdtb monitor commands

The boston machine doesn't set MachineState::fdt to the DTB blob that
it has loaded or created, which means that the QMP/HMP dumpdtb
monitor commands don't work.

Setting MachineState::fdt is easy in the non-FIT codepath: we can
simply do so immediately before loading the DTB into guest memory.
The FIT codepath is a bit more awkward as currently the FIT loader
throws away the memory that the FDT was in after it loads it into
guest memory.  So we add a void *pfdt argument to load_fit() for it
to store the FDT pointer into.

There is some readjustment required of the pointer handling in
loader-fit.c, so that it applies 'const' only where it should (e.g.
the data pointer we get back from fdt_getprop() is const, because
it's into the middle of the input FDT data, but the pointer that
fit_load_image_alloc() should not be const, because it's freshly
allocated memory that the caller can change if it likes).

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20250206151214.2947842-5-peter.maydell@linaro.org

1 files changed, 7 insertions, 4 deletions

diff --git a/hw/mips/boston.c b/hw/mips/boston.c
index de6ce1f163..79410dabe7 100644
--- a/hw/mips/boston.c
+++ b/hw/mips/boston.c
@@ -358,8 +358,8 @@ static void gen_firmware(void *p, hwaddr kernel_entry, hwaddr fdt_addr)
                        kernel_entry);
 }
 
-static const void *boston_fdt_filter(void *opaque, const void *fdt_orig,
-                                     const void *match_data, hwaddr *load_addr)
+static void *boston_fdt_filter(void *opaque, const void *fdt_orig,
+                               const void *match_data, hwaddr *load_addr)
 {
     BostonState *s = BOSTON(opaque);
     MachineState *machine = s->mach;
@@ -797,7 +797,7 @@ static void boston_mach_init(MachineState *machine)
         if (kernel_size > 0) {
             int dt_size;
             g_autofree const void *dtb_file_data = NULL;
-            g_autofree const void *dtb_load_data = NULL;
+            void *dtb_load_data = NULL;
             hwaddr dtb_paddr = QEMU_ALIGN_UP(kernel_high, 64 * KiB);
             hwaddr dtb_vaddr = cpu_mips_phys_to_kseg0(NULL, dtb_paddr);
 
@@ -815,6 +815,8 @@ static void boston_mach_init(MachineState *machine)
                 exit(1);
             }
 
+            machine->fdt = dtb_load_data;
+
             /* Calculate real fdt size after filter */
             dt_size = fdt_totalsize(dtb_load_data);
             rom_add_blob_fixed("dtb", dtb_load_data, dt_size, dtb_paddr);
@@ -822,7 +824,8 @@ static void boston_mach_init(MachineState *machine)
                                 rom_ptr(dtb_paddr, dt_size));
         } else {
             /* Try to load file as FIT */
-            fit_err = load_fit(&boston_fit_loader, machine->kernel_filename, s);
+            fit_err = load_fit(&boston_fit_loader, machine->kernel_filename,
+                               &machine->fdt, s);
             if (fit_err) {
                 error_report("unable to load kernel image");
                 exit(1);