[U-Boot] [RFC PATCH 10/12] linux_compat: introduce GFP_DMA flag for kmalloc()

[Heiko Schocher <hs@denx.de>]

Hello Masahiro,

Am 08.07.2015 um 06:29 schrieb Masahiro Yamada:
> It does not seem efficient to always return cache-aligned memory.
> Return aligned memory only when GFP_DMA flag is given.
>
> My main motivation for this commit is to refactor device_probe()
> and device_free() in the next commit.  DM_FLAG_ALLOC_PRIV_DMA
> should be handled more easily.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
>   include/linux/compat.h | 1 +
>   lib/linux_compat.c     | 5 ++++-
>   2 files changed, 5 insertions(+), 1 deletion(-)

Hmm... I think there are a lot of places in code, where implicit
is supposed, that kmalloc returns aligned memory ... so this
patch needs testing (USB, DFU and ethernet coming in my mind)

bye,
Heiko
>
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 64988bf..8b7f8ef 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -41,6 +41,7 @@ extern struct p_current *current;
>   #define GFP_NOFS ((gfp_t) 0)
>   #define GFP_USER ((gfp_t) 0)
>   #define __GFP_NOWARN ((gfp_t) 0)
> +#define GFP_DMA		((__force gfp_t)0x01u)
>   #define __GFP_ZERO	((__force gfp_t)0x8000u) /* Return zeroed page on success */
>
>   void *kmalloc(size_t size, int flags);
> diff --git a/lib/linux_compat.c b/lib/linux_compat.c
> index a936a7e..6da0cfa 100644
> --- a/lib/linux_compat.c
> +++ b/lib/linux_compat.c
> @@ -18,7 +18,10 @@ void *kmalloc(size_t size, int flags)
>   {
>   	void *p;
>
> -	p = memalign(ARCH_DMA_MINALIGN, size);
> +	if (flags & GFP_DMA)
> +		p = memalign(ARCH_DMA_MINALIGN, size);
> +	else
> +		p = malloc(size);
>   	if (flags & __GFP_ZERO)
>   		memset(p, 0, size);
>
>

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