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Re: [Qemu-block] [PATCH 1/1] ide: unify io_buffer_offset increments
From: |
Paolo Bonzini |
Subject: |
Re: [Qemu-block] [PATCH 1/1] ide: unify io_buffer_offset increments |
Date: |
Mon, 7 Sep 2015 18:37:35 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 |
On 26/08/2015 01:45, John Snow wrote:
> IDEState's io_buffer_offset was originally added to keep track of offsets
> in AHCI rather exclusively, but it was added to IDEState instead of an
> AHCI-specific structure.
Interesting to see something weird turn into feature. :)
Reviewed-by: Paolo Bonzini <address@hidden>
> AHCI fakes all PIO transfers using DMA and a scatter-gather list. When
> the core or atapi layers invoke HBA-specific mechanisms for transfers,
> they do not always know that it is being backed by DMA or a sglist, so
> this offset is not always updated by the HBA code everywhere.
>
> If we modify it in dma_buf_commit, however, any HBA that needs to use
> this offset to manage operating on only part of a sglist will have
> access to it.
>
> This will fix ATAPI PIO transfers performed through the AHCI HBA,
> which were previously not modifying this value appropriately.
>
> This will fix ATAPI PIO transfers larger than one sector.
- Re: [Qemu-block] [PATCH 1/1] ide: unify io_buffer_offset increments,
Paolo Bonzini <=