[PULL 1/1] hw/loongarch: Fix loongarch fdt addr confict

[Richard Henderson]

From: Song Gao <gaosong@loongson.cn>

Fix LoongArch check-tcg error:
   TEST    hello on loongarch64
qemu-system-loongarch64: Some ROM regions are overlapping
These ROM regions might have been loaded by direct user request or by default.
They could be BIOS/firmware images, a guest kernel, initrd or some other file 
loaded into guest memory.
Check whether you intended to load all this guest code, and whether it has been 
built to load to the correct addresses.

The following two regions overlap (in the memory address space):
   hello ELF program header segment 0 (addresses 0x0000000000200000 - 
0x0000000000242000)
   fdt (addresses 0x0000000000200000 - 0x0000000000300000)
make[1]: *** [Makefile:177: run-hello] Error 1

Fixes: 021836936ef ("hw/loongarch: Load FDT table into dram memory space")
Reported-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20221109020449.978064-1-gaosong@loongson.cn>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 hw/loongarch/virt.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/hw/loongarch/virt.c b/hw/loongarch/virt.c
index 5e4c2790bf..5136940b0b 100644
--- a/hw/loongarch/virt.c
+++ b/hw/loongarch/virt.c
@@ -793,13 +793,13 @@ static void loongarch_init(MachineState *machine)
     qemu_add_machine_init_done_notifier(&lams->machine_done);
     fdt_add_pcie_node(lams);
     /*
-     * Since lowmem region starts from 0, FDT base address is located
-     * at 2 MiB to avoid NULL pointer access.
-     *
+     * Since lowmem region starts from 0 and Linux kernel legacy start address
+     * at 2 MiB, FDT base address is located at 1 MiB to avoid NULL pointer
+     * access. FDT size limit with 1 MiB.
      * Put the FDT into the memory map as a ROM image: this will ensure
      * the FDT is copied again upon reset, even if addr points into RAM.
      */
-    fdt_base = 2 * MiB;
+    fdt_base = 1 * MiB;
     qemu_fdt_dumpdtb(machine->fdt, lams->fdt_size);
     rom_add_blob_fixed("fdt", machine->fdt, lams->fdt_size, fdt_base);
 }
-- 
2.34.1