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Re: [Qemu-devel] [PATCH] arm: add device tree support


From: Anthony Liguori
Subject: Re: [Qemu-devel] [PATCH] arm: add device tree support
Date: Mon, 27 Feb 2012 11:41:13 -0600
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.23) Gecko/20110922 Lightning/1.0b2 Thunderbird/3.1.15

On 02/27/2012 11:38 AM, Peter Maydell wrote:
From: Grant Likely<address@hidden>

If compiled with CONFIG_FDT, allow user to specify a device tree file using
the -dtb argument.  If the machine supports it then the dtb will be loaded
into memory and passed to the kernel on boot.

Signed-off-by: Jeremy Kerr<address@hidden>
Signed-off-by: Grant Likely<address@hidden>
[Peter Maydell: Use machine opt rather than global to pass dtb filename]
Signed-off-by: Peter Maydell<address@hidden>

Reviewed-by: Anthony Liguori <address@hidden>

Thanks for doing the work to wrap this in QemuOpts.  This was a nice 
improvement.

Regards,

Anthony Liguori

---
v1->v2: fix potential NULL deref if qemu_opts_find() returns NULL

  Makefile.target |    1 +
  configure       |    1 +
  hw/arm-misc.h   |    1 +
  hw/arm_boot.c   |  102 +++++++++++++++++++++++++++++++++++++++++++++++++++---
  qemu-config.c   |    4 ++
  qemu-options.hx |    9 +++++
  vl.c            |    8 ++++
  7 files changed, 120 insertions(+), 6 deletions(-)

diff --git a/Makefile.target b/Makefile.target
index 68a5641..6a56b3e 100644
--- a/Makefile.target
+++ b/Makefile.target
@@ -373,6 +373,7 @@ obj-arm-y += vexpress.o
  obj-arm-y += strongarm.o
  obj-arm-y += collie.o
  obj-arm-y += pl041.o lm4549.o
+obj-arm-$(CONFIG_FDT) += device_tree.o

  obj-sh4-y = shix.o r2d.o sh7750.o sh7750_regnames.o tc58128.o
  obj-sh4-y += sh_timer.o sh_serial.o sh_intc.o sh_pci.o sm501.o
diff --git a/configure b/configure
index f9d5330..7d509e8 100755
--- a/configure
+++ b/configure
@@ -3472,6 +3472,7 @@ case "$target_arch2" in
      gdb_xml_files="arm-core.xml arm-vfp.xml arm-vfp3.xml arm-neon.xml"
      target_phys_bits=32
      target_llong_alignment=4
+    target_libs_softmmu="$fdt_libs"
    ;;
    cris)
      target_nptl="yes"
diff --git a/hw/arm-misc.h b/hw/arm-misc.h
index 306013a..734bd82 100644
--- a/hw/arm-misc.h
+++ b/hw/arm-misc.h
@@ -29,6 +29,7 @@ struct arm_boot_info {
      const char *kernel_filename;
      const char *kernel_cmdline;
      const char *initrd_filename;
+    const char *dtb_filename;
      target_phys_addr_t loader_start;
      /* multicore boards that use the default secondary core boot functions
       * need to put the address of the secondary boot code, the boot reg,
diff --git a/hw/arm_boot.c b/hw/arm_boot.c
index 2ef25ca..fc66910 100644
--- a/hw/arm_boot.c
+++ b/hw/arm_boot.c
@@ -7,11 +7,14 @@
   * This code is licensed under the GPL.
   */

+#include "config.h"
  #include "hw.h"
  #include "arm-misc.h"
  #include "sysemu.h"
+#include "boards.h"
  #include "loader.h"
  #include "elf.h"
+#include "device_tree.h"

  #define KERNEL_ARGS_ADDR 0x100
  #define KERNEL_LOAD_ADDR 0x00010000
@@ -208,6 +211,67 @@ static void set_kernel_args_old(const struct arm_boot_info 
*info)
      }
  }

+static int load_dtb(target_phys_addr_t addr, const struct arm_boot_info *binfo)
+{
+#ifdef CONFIG_FDT
+    uint32_t mem_reg_property[] = { cpu_to_be32(binfo->loader_start),
+                                    cpu_to_be32(binfo->ram_size) };
+    void *fdt = NULL;
+    char *filename;
+    int size, rc;
+
+    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, binfo->dtb_filename);
+    if (!filename) {
+        fprintf(stderr, "Couldn't open dtb file %s\n", binfo->dtb_filename);
+        return -1;
+    }
+
+    fdt = load_device_tree(filename,&size);
+    if (!fdt) {
+        fprintf(stderr, "Couldn't open dtb file %s\n", filename);
+        g_free(filename);
+        return -1;
+    }
+    g_free(filename);
+
+    rc = qemu_devtree_setprop(fdt, "/memory", "reg", mem_reg_property,
+                               sizeof(mem_reg_property));
+    if (rc<  0) {
+        fprintf(stderr, "couldn't set /memory/reg\n");
+    }
+
+    rc = qemu_devtree_setprop_string(fdt, "/chosen", "bootargs",
+                                      binfo->kernel_cmdline);
+    if (rc<  0) {
+        fprintf(stderr, "couldn't set /chosen/bootargs\n");
+    }
+
+    if (binfo->initrd_size) {
+        rc = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-start",
+                binfo->loader_start + INITRD_LOAD_ADDR);
+        if (rc<  0) {
+            fprintf(stderr, "couldn't set /chosen/linux,initrd-start\n");
+        }
+
+        rc = qemu_devtree_setprop_cell(fdt, "/chosen", "linux,initrd-end",
+                    binfo->loader_start + INITRD_LOAD_ADDR +
+                    binfo->initrd_size);
+        if (rc<  0) {
+            fprintf(stderr, "couldn't set /chosen/linux,initrd-end\n");
+        }
+    }
+
+    cpu_physical_memory_write(addr, fdt, size);
+
+    return 0;
+
+#else
+    fprintf(stderr, "Device tree requested, "
+                "but qemu was compiled without fdt support\n");
+    return -1;
+#endif
+}
+
  static void do_cpu_reset(void *opaque)
  {
      CPUState *env = opaque;
@@ -222,10 +286,12 @@ static void do_cpu_reset(void *opaque)
          } else {
              if (env == first_cpu) {
                  env->regs[15] = info->loader_start;
-                if (old_param) {
-                    set_kernel_args_old(info);
-                } else {
-                    set_kernel_args(info);
+                if (!info->dtb_filename) {
+                    if (old_param) {
+                        set_kernel_args_old(info);
+                    } else {
+                        set_kernel_args(info);
+                    }
                  }
              } else {
                  info->secondary_cpu_reset_hook(env, info);
@@ -243,6 +309,7 @@ void arm_load_kernel(CPUState *env, struct arm_boot_info 
*info)
      uint64_t elf_entry;
      target_phys_addr_t entry;
      int big_endian;
+    QemuOpts *machine_opts;

      /* Load the kernel.  */
      if (!info->kernel_filename) {
@@ -250,6 +317,13 @@ void arm_load_kernel(CPUState *env, struct arm_boot_info 
*info)
          exit(1);
      }

+    machine_opts = qemu_opts_find(qemu_find_opts("machine"), 0);
+    if (machine_opts) {
+        info->dtb_filename = qemu_opt_get(machine_opts, "dtb");
+    } else {
+        info->dtb_filename = NULL;
+    }
+
      if (!info->secondary_cpu_reset_hook) {
          info->secondary_cpu_reset_hook = default_reset_secondary;
      }
@@ -300,8 +374,25 @@ void arm_load_kernel(CPUState *env, struct arm_boot_info 
*info)
          } else {
              initrd_size = 0;
          }
+        info->initrd_size = initrd_size;
+
          bootloader[4] = info->board_id;
-        bootloader[5] = info->loader_start + KERNEL_ARGS_ADDR;
+
+        /* for device tree boot, we pass the DTB directly in r2. Otherwise
+         * we point to the kernel args.
+         */
+        if (info->dtb_filename) {
+            /* Place the DTB after the initrd in memory */
+            target_phys_addr_t dtb_start = TARGET_PAGE_ALIGN(info->loader_start
+                                                             + INITRD_LOAD_ADDR
+                                                             + initrd_size);
+            if (load_dtb(dtb_start, info)) {
+                exit(1);
+            }
+            bootloader[5] = dtb_start;
+        } else {
+            bootloader[5] = info->loader_start + KERNEL_ARGS_ADDR;
+        }
          bootloader[6] = entry;
          for (n = 0; n<  sizeof(bootloader) / 4; n++) {
              bootloader[n] = tswap32(bootloader[n]);
@@ -311,7 +402,6 @@ void arm_load_kernel(CPUState *env, struct arm_boot_info 
*info)
          if (info->nb_cpus>  1) {
              info->write_secondary_boot(env, info);
          }
-        info->initrd_size = initrd_size;
      }
      info->is_linux = is_linux;

diff --git a/qemu-config.c b/qemu-config.c
index 7d9da78..be84a03 100644
--- a/qemu-config.c
+++ b/qemu-config.c
@@ -578,6 +578,10 @@ static QemuOptsList qemu_machine_opts = {
              .name = "append",
              .type = QEMU_OPT_STRING,
              .help = "Linux kernel command line",
+        }, {
+            .name = "dtb",
+            .type = QEMU_OPT_STRING,
+            .help = "Linux kernel device tree file",
          },
          { /* End of list */ }
      },
diff --git a/qemu-options.hx b/qemu-options.hx
index b129996..e38799c 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -2037,6 +2037,15 @@ Use @var{file1} and @var{file2} as modules and pass 
arg=foo as parameter to the
  first module.
  ETEXI

+DEF("dtb", HAS_ARG, QEMU_OPTION_dtb, \
+    "-dtb    file    use 'file' as device tree image\n", QEMU_ARCH_ARM)
+STEXI
address@hidden -dtb @var{file}
address@hidden -dtb
+Use @var{file} as a device tree binary (dtb) image and pass it to the kernel
+on boot.
+ETEXI
+
  STEXI
  @end table
  ETEXI
diff --git a/vl.c b/vl.c
index 1d4c350..2d3347d 100644
--- a/vl.c
+++ b/vl.c
@@ -2526,6 +2526,9 @@ int main(int argc, char **argv, char **envp)
              case QEMU_OPTION_append:
                  qemu_opts_set(qemu_find_opts("machine"), 0, "append", optarg);
                  break;
+            case QEMU_OPTION_dtb:
+                qemu_opts_set(qemu_find_opts("machine"), 0, "dtb", optarg);
+                break;
              case QEMU_OPTION_cdrom:
                  drive_add(IF_DEFAULT, 2, optarg, CDROM_OPTS);
                  break;
@@ -3345,6 +3348,11 @@ int main(int argc, char **argv, char **envp)
          exit(1);
      }

+    if (!linux_boot&&  machine_opts&&  qemu_opt_get(machine_opts, "dtb")) {
+        fprintf(stderr, "-dtb only allowed with -kernel option\n");
+        exit(1);
+    }
+
      os_set_line_buffering();

      if (init_timer_alarm()<  0) {




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