Subject: Re: linux-next: build failure after merge of the akpm-current tree

From: Santosh Shilimkar <[email-masked]>
Date: Mon, 6 Jan 2014 10:06:15 -0500

Stephen,

On Monday 06 January 2014 04:07 AM, Stephen Rothwell wrote:
> Hi Andrew,
> 
> After merging the akpm-current tree, today's linux-next build (arm
> multi_v7_defconfig) failed like this:
> 
> arch/arm/mm/init.c:199:13: error: conflicting types for 'arm_dma_zone_size'
> include/linux/bootmem.h:259:11: note: previous declaration of 'arm_dma_zone_size' was here
> 
> Caused by commit a3ae9362fafe ("mm/memblock: add memblock memory
> allocation apis").
>
> For this build, BOOTMEM_LOW_LIMIT is defined as __pa(MAX_DMA_ADDRESS) and
> MAX_DMA_ADDRESS is defined as:
> 
> #define MAX_DMA_ADDRESS ({ \
>         extern unsigned long arm_dma_zone_size; \
>         arm_dma_zone_size ? \
>                 (PAGE_OFFSET + arm_dma_zone_size) : 0xffffffffUL; })
> 
> and in arch/arm/mm/init.c, arm_dma_zone_size is declared as:
> 
> phys_addr_t arm_dma_zone_size __read_mostly;
> 
> Urk!  :-(
> 
> OK, so commit 364230b995214 ("ARM: use phys_addr_t for DMA zone sizes")
> changed the definition of arm_dma_zone_size except it missed the one in
> arch/arm/include/asm/dma.h.
> 
> I have applied this merge fix patch for today:
> 
The issue was detected earlier and similar patch to yours
was proposed here [1]. But the fix isn't right as rightly
commented by Russell because the DMA_MAX_ADDRESS is a virtual
address which can't be more than 4 GB. Need to figure out
the right fix though.

Regards,
Santosh
[1] http://www.spinics.net/lists/arm-kernel/msg292905.html