Re: [Qemu-devel] [PATCH] honor IDE_DMA_BUF_SECTORS

[Avi Kivity]

Stefano Stabellini wrote:
> Avi Kivity wrote:
>
>   
> > Stefano Stabellini wrote:
> >     
> > > Hi all,
> > > after the recent introduction of dma_buf_prepare we stopped honoring
> > > IDE_DMA_BUF_SECTORS (the guest can issue dma requests with a greater
> > > total length than IDE_DMA_BUF_SECTORS).
> > > This patch adds the IDE_DMA_BUF_SECTORS limit back in place.
> > >
> > > Comments are welcome.
> > >   
> > >       
> > Aren't 64K sector requests legal?
> >
> > Looking at ide_cmd_lba48_transform().
> >
> >     
>
>
> I am not sure about that, but I would think not since we define 
> MAX_MULT_SECTORS 16
> If I change MAX_MULT_SECTORS, am I supposed to see smaller dma requests?
>   

I think that's for pio, or maybe older DMA?  Certainly you wouldn't 
expect to be limited to 16 sectors DMA.

Anyway I think IDE_DMA_BUF_SECTORS was a qemu limitation and did not 
model real hardware behaviour.

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