Re: [PATCH v7 04/14] hw/ppc: set machine->fdt in ppce500_load_device_tree()

[Philippe Mathieu-Daudé]

+David/Peter

On 8/9/22 21:40, Daniel Henrique Barboza wrote:
> This will enable support for 'dumpdtb' QMP/HMP command for the e500
> machine.
>
> Cc: Cédric Le Goater <clg@kaod.org>
> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>
> ---
>   hw/ppc/e500.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
> index 32495d0123..ea5f947824 100644
> --- a/hw/ppc/e500.c
> +++ b/hw/ppc/e500.c
> @@ -47,6 +47,8 @@
>   #include "hw/i2c/i2c.h"
>   #include "hw/irq.h"
>   
> +#include <libfdt.h>
> +
>   #define EPAPR_MAGIC                (0x45504150)
>   #define DTC_LOAD_PAD               0x1800000
>   #define DTC_PAD_MASK               0xFFFFF
> @@ -600,7 +602,16 @@ done:
>           cpu_physical_memory_write(addr, fdt, fdt_size);
>       }
>       ret = fdt_size;
> -    g_free(fdt);
> +
> +    /*
> +     * Update the machine->fdt pointer to enable support for the
> +     * 'dumpdtb' QMP/HMP command.
> +     *
> +     * The FDT is re-created during reset,

Why are we doing that? Is it really necessary? This seems to be only 
required at cold power-on.

> so free machine->fdt
> +     * to avoid leaking the old FDT.
> +     */
> +    g_free(machine->fdt);
> +    machine->fdt = fdt;
>   
>   out:
>       g_free(pci_map);