Re: [Qemu-devel] [PATCH v2 3/3] hw/arm/virt: Silence dtc /memory warning

[Peter Maydell]

On 18 June 2018 at 13:46, Eric Auger <address@hidden> wrote:
> When running dtc on the guest /proc/device-tree we get the
> following warning: Warning (unit_address_vs_reg): Node /memory
> has a reg or ranges property, but no unit name".
>
> Let's fix that by adding the unit address to the node name. We also
> don't create the /memory node anymore in create_fdt(). We directly
> create it in load_dtb. /chosen still needs to be created in create_fdt
> as the uart needs it. In case the user provided his own dtb, we nop
> all memory nodes and create new one(s).
>
> Signed-off-by: Eric Auger <address@hidden>
> ---
>  hw/arm/boot.c | 34 ++++++++++++++++++++--------------
>  hw/arm/virt.c |  7 +------
>  2 files changed, 21 insertions(+), 20 deletions(-)
>
> diff --git a/hw/arm/boot.c b/hw/arm/boot.c
> index 1e48166..de80d05 100644
> --- a/hw/arm/boot.c
> +++ b/hw/arm/boot.c
> @@ -490,11 +490,13 @@ int arm_load_dtb(hwaddr addr, const struct 
> arm_boot_info *binfo,
>                   hwaddr addr_limit, AddressSpace *as)
>  {
>      void *fdt = NULL;
> -    int size, rc;
> +    int size, rc, n = 0;
>      uint32_t acells, scells;
>      char *nodename;
>      unsigned int i;
>      hwaddr mem_base, mem_len;
> +    char **node_path;
> +    Error *err = NULL;
>
>      if (binfo->dtb_filename) {
>          char *filename;
> @@ -546,12 +548,22 @@ int arm_load_dtb(hwaddr addr, const struct 
> arm_boot_info *binfo,
>          goto fail;
>      }
>
> +    /* nop all nodes matching /memory or /address@hidden */
> +    node_path = qemu_fdt_node_unit_path(fdt, "memory", &err);
> +    if (err) {
> +        error_report_err(err);
> +        goto fail;
> +    }
> +    while (node_path[n]) {
> +        qemu_fdt_nop_node(fdt, node_path[n++]);
> +    }
> +    g_strfreev(node_path);

This removes all nodes named "memory" or "address@hidden", rather than
just the ones in the root, right? Is that definitely what we want to
do? The old code only deleted /memory, and the comment implies
that we only look in the root.

(I'm wondering if there are DTs that use memory nodes for random
odd things other than system memory...)

> +
>      if (nb_numa_nodes > 0) {
>          /*
>           * Turn the /memory node created before into a NOP node, then create
>           * /address@hidden nodes for all numa nodes respectively.
>           */
> -        qemu_fdt_nop_node(fdt, "/memory");

This code change means the comment needs updating too.

>          mem_base = binfo->loader_start;
>          for (i = 0; i < nb_numa_nodes; i++) {
>              mem_len = numa_info[i].node_mem;
> @@ -572,24 +584,18 @@ int arm_load_dtb(hwaddr addr, const struct 
> arm_boot_info *binfo,
>              g_free(nodename);
>          }
>      } else {
> -        Error *err = NULL;
> +        nodename = g_strdup_printf("/address@hidden" PRIx64, 
> binfo->loader_start);
> +        qemu_fdt_add_subnode(fdt, nodename);
> +        qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
>
> -        rc = fdt_path_offset(fdt, "/memory");
> -        if (rc < 0) {
> -            qemu_fdt_add_subnode(fdt, "/memory");
> -        }
> -
> -        if (!qemu_fdt_getprop(fdt, "/memory", "device_type", NULL, &err)) {
> -            qemu_fdt_setprop_string(fdt, "/memory", "device_type", "memory");
> -        }
> -
> -        rc = qemu_fdt_setprop_sized_cells(fdt, "/memory", "reg",
> +        rc = qemu_fdt_setprop_sized_cells(fdt, nodename, "reg",
>                                            acells, binfo->loader_start,
>                                            scells, binfo->ram_size);
>          if (rc < 0) {
> -            fprintf(stderr, "couldn't set /memory/reg\n");
> +            fprintf(stderr, "couldn't set %s reg\n", nodename);
>              goto fail;
>          }
> +        g_free(nodename);
>      }
>
>      rc = fdt_path_offset(fdt, "/chosen");
> diff --git a/hw/arm/virt.c b/hw/arm/virt.c
> index cd0f350..71c27f1 100644
> --- a/hw/arm/virt.c
> +++ b/hw/arm/virt.c
> @@ -200,13 +200,8 @@ static void create_fdt(VirtMachineState *vms)
>      qemu_fdt_setprop_cell(fdt, "/", "#address-cells", 0x2);
>      qemu_fdt_setprop_cell(fdt, "/", "#size-cells", 0x2);
>
> -    /*
> -     * /chosen and /memory nodes must exist for load_dtb
> -     * to fill in necessary properties later
> -     */
> +    /* /chosen must exist for load_dtb to fill in necessary properties later 
> */
>      qemu_fdt_add_subnode(fdt, "/chosen");
> -    qemu_fdt_add_subnode(fdt, "/memory");
> -    qemu_fdt_setprop_string(fdt, "/memory", "device_type", "memory");
>
>      /* Clock node, for the benefit of the UART. The kernel device tree
>       * binding documentation claims the PL011 node clock properties are
> --
> 2.5.5

thanks
-- PMM