svn commit: r209026 - in head/sys/ia64: ia64 include

[Marcel Moolenaar]

On Jun 11, 2010, at 10:47 AM, Scott Long wrote:

> On Jun 11, 2010, at 11:44 AM, Marcel Moolenaar wrote:
>> 
>> On Jun 11, 2010, at 10:37 AM, Scott Long wrote:
>>> 
>>> I'm not clear why you even need bounce buffers for RX.  The chip supports 64bit addresses with no boundary or alignment restrictions.
>> 
>> As per:
>>       /*
>>        * All controllers that are not 5755 or higher have 4GB
>>        * boundary DMA bug.
>>        * Whenever an address crosses a multiple of the 4GB boundary
>>        * (including 4GB, 8Gb, 12Gb, etc.) and makes the transition
>>        * from 0xX_FFFF_FFFF to 0x(X+1)_0000_0000 an internal DMA
>>        * state machine will lockup and cause the device to hang.
>>        */
>>       if (BGE_IS_5755_PLUS(sc) == 0)
>>               sc->bge_flags |= BGE_FLAG_4G_BNDRY_BUG;
>> 
>> and:
>>       lowaddr = BUS_SPACE_MAXADDR;
>>       if ((sc->bge_flags & BGE_FLAG_40BIT_BUG) != 0)
>>               lowaddr = BGE_DMA_MAXADDR;
>>       if ((sc->bge_flags & BGE_FLAG_4G_BNDRY_BUG) != 0)
>>               lowaddr = BUS_SPACE_MAXADDR_32BIT;
>>       /*
>>        * Allocate the parent bus DMA tag appropriate for PCI.
>>        */
>>       error = bus_dma_tag_create(bus_get_dma_tag(sc->bge_dev),
>>           1, 0, lowaddr, BUS_SPACE_MAXADDR, NULL,
>>           NULL, BUS_SPACE_MAXSIZE_32BIT, 0, BUS_SPACE_MAXSIZE_32BIT,
>>           0, NULL, NULL, &sc->bge_cdata.bge_parent_tag);
>> 
>> 
> 
> Noted in previous email.  If this restriction is put in the boundary attribute, then you'll only bounce the very rare case of an mbuf straddling a 4G boundary.

I agree with you, but I was just giving the facts. I don't even
know if we attempted to use the boundary argument before but
problems forced us to resort to this.

-- 
Marcel Moolenaar
xcllnt at mac.com