svn commit: r217330 - head/sys/x86/x86

[mdf at FreeBSD.org]

On Wed, Jan 12, 2011 at 1:21 PM, John Baldwin <jhb at freebsd.org> wrote:
> On Wednesday, January 12, 2011 4:08:50 pm Matthew D Fleming wrote:
>> Author: mdf
>> Date: Wed Jan 12 21:08:49 2011
>> New Revision: 217330
>> URL: http://svn.freebsd.org/changeset/base/217330
>>
>> Log:
>>   Fix a brain fart.  Since this file is shared between i386 and amd64, a
>>   bus_size_t may be 32 or 64 bits.  Change the bounce_zone alignment field
>>   to explicitly be 32 bits, as I can't really imagine a DMA device that
>>   needs anything close to 2GB alignment of data.
>
> Hmm, we do have devices with 4GB boundaries though.  I think I'd prefer it if
> you instead if you did this:
>
> #if defined(amd64) || defined(PAE)
> #define SYSCTL_ADD_BUS_SIZE_T           SYSCTL_ADD_UQUAD
> #else
> #define SYSCTL_ADD_BUS_SIZE_T           SYSCTL_ADD_UINT
> #endif
>
> and then just used SYSCTL_ADD_BUS_SIZE_T() in the code so we could let the
> members in the bounce zone retain the same types passed to
> bus_dma_tag_create().

But would there be a device that can't start DMA except on a 4GB
boundary?  I thought that's what this member was for.

Thanks,
matthew