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Subject: Re: [patch 1/2] bootmem: add alloc_bootmem_align()
From: Suresh Siddha <suresh.b.siddha@intel.com>
Reply-To: Suresh Siddha <suresh.b.siddha@intel.com>
To: "H. Peter Anvin" <hpa@linux.intel.com>
Cc: "hpa@zytor.com" <hpa@zytor.com>, "mingo@elte.hu" <mingo@elte.hu>,
        "tglx@linutronix.de" <tglx@linutronix.de>,
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        "H. Peter Anvin" <hpa@linux.jf.intel.com>
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Organization: Intel Corp
Date: Tue, 16 Nov 2010 16:06:50 -0800
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On Tue, 2010-11-16 at 14:14 -0800, H. Peter Anvin wrote:
> On 11/16/2010 01:23 PM, Suresh Siddha wrote:
> > Index: tree/include/linux/bootmem.h
> > ===================================================================
> > --- tree.orig/include/linux/bootmem.h
> > +++ tree/include/linux/bootmem.h
> > @@ -105,6 +105,8 @@ extern void *__alloc_bootmem_low_node(pg
> >  
> >  #define alloc_bootmem(x) \
> >  	__alloc_bootmem(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
> > +#define alloc_bootmem_align(x, align) \
> > +	__alloc_bootmem(x, align, __pa(MAX_DMA_ADDRESS))
> >  #define alloc_bootmem_nopanic(x) \
> >  	__alloc_bootmem_nopanic(x, SMP_CACHE_BYTES, __pa(MAX_DMA_ADDRESS))
> >  #define alloc_bootmem_pages(x) \
> 
>   [...]
> 
> >  	 */
> > -	init_xstate_buf = alloc_bootmem(xstate_size);
> > +	init_xstate_buf = alloc_bootmem_align(xstate_size,
> > +					      __alignof__(struct xsave_struct));
> >  	init_xstate_buf->i387.mxcsr = MXCSR_DEFAULT;
> 
> Perhaps it would make even more sense to have:
> 
> #define alloc_bootmem_alignof(x, type) \
> 	__alloc_bootmem(x, __alignof__(type), __pa(MAX_DMA_ADDRESS))
> 

Wanted to keep it broad so that more people can start using it.

For example, most of the current x86 uses of alloc_bootmem_pages() (or
the __alloc_bootmem() calls in other architectures) can be replaced with
alloc_bootmem_align() and most of them don't have a relevant type to
describe the alignment.

thanks,
suresh