Re: [Qemu-devel] [PATCH 02/13] Implement cpu_physical_memory_set()

[Anthony Liguori <anthony@codemonkey.ws>]

On 06/19/2012 01:39 AM, Benjamin Herrenschmidt wrote:
> From: David Gibson<david@gibson.dropbear.id.au>
>
> This patch adds cpu_physical_memory_set() function.  This is equivalent to
> calling cpu_physical_memory_write() with a buffer filled with a character,
> ie, a memset of target memory.
>
> It uses a small temporary buffer on the stack.
>
> Signed-off-by: David Gibson<david@gibson.dropbear.id.au>
> Signed-off-by: Benjamin Herrenschmidt<benh@kernel.crashing.org>

Why should this be in the core API?  Shouldn't this be a helper on top of the 
DMA API?

Regards,

Anthony Liguori

> ---
>   cpu-common.h |    1 +
>   exec.c       |   15 +++++++++++++++
>   2 files changed, 16 insertions(+)
>
> diff --git a/cpu-common.h b/cpu-common.h
> index 1fe3280..8d3596a 100644
> --- a/cpu-common.h
> +++ b/cpu-common.h
> @@ -53,6 +53,7 @@ void qemu_ram_set_idstr(ram_addr_t addr, const char *name, DeviceState *dev);
>
>   void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
>                               int len, int is_write);
> +void cpu_physical_memory_set(target_phys_addr_t addr, uint8_t c, int len);
>   static inline void cpu_physical_memory_read(target_phys_addr_t addr,
>                                               void *buf, int len)
>   {
> diff --git a/exec.c b/exec.c
> index b5d6885..cfd7008 100644
> --- a/exec.c
> +++ b/exec.c
> @@ -3601,6 +3601,21 @@ void cpu_physical_memory_rw(target_phys_addr_t addr, uint8_t *buf,
>       }
>   }
>
> +void cpu_physical_memory_set(target_phys_addr_t addr, uint8_t c, int len)
> +{
> +#define FILLBUF_SIZE 512
> +    uint8_t fillbuf[FILLBUF_SIZE];
> +    int l;
> +
> +    memset(fillbuf, c, FILLBUF_SIZE);
> +    while (len>  0) {
> +        l = len<  FILLBUF_SIZE ? len : FILLBUF_SIZE;
> +        cpu_physical_memory_rw(addr, fillbuf, l, true);
> +        len -= len;
> +        addr += len;
> +    }
> +}
> +
>   /* used for ROM loading : can write in RAM and ROM */
>   void cpu_physical_memory_write_rom(target_phys_addr_t addr,
>                                      const uint8_t *buf, int len)