Re: [Qemu-devel] [RFC 0/2] macio: split out unaligned DMA access into separate functions

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Mon, Mar 09, 2015 at 10:24:51PM +0000, Mark Cave-Ayland wrote:
> This patchset attempts to separate out the IDE/ATAPI logic from the unaligned
> DMA access logic for macio which provides the following benefits:
> 
> 1) Reduced code complexity
> 
> The existing macio IDE/ATAPI functions were becoming extremely difficult to
> follow through the various callbacks. By splitting up the functions in this
> way it becomes much easier to follow the DMA-specific sections of code.
> 
> 2) Future-proofing
> 
> If/when the block layer becomes able to handle unaligned DMA accesses directly
> then it should be possible to switch out pmac_dma_read() and pmac_dma_write()
> with their unaligned-capable bdrv_*() equivalents without having to change any
> other logic.
> 
> 3) Fix intermittent CDROM detection under -M g3beige
> 
> The code refactoring now correctly handles non-block ATAPI transfers which
> fixes the problem with intermittent CDROM detection with Darwin under
> -M g3beige.
> 
> Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
> 
> 
> Mark Cave-Ayland (2):
>   macio: move unaligned DMA read code into separate pmac_dma_read()
>     function
>   macio: move unaligned DMA write code into separate pmac_dma_write()
>     function
> 
>  hw/ide/macio.c             |  487 +++++++++++++++++++++++---------------------
>  include/hw/ppc/mac_dbdma.h |    4 -
>  2 files changed, 254 insertions(+), 237 deletions(-)

CCing John Snow, who is now maintaining IDE/ATAPI/AHCI.

Stefan

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