Dear David > -----Original Message----- > From: David Vrabel [mailto:david.vrabel@xxxxxxxxxx] > Sent: Tuesday, February 10, 2015 5:46 PM > To: Wang, Xiaoming; Konrad Rzeszutek Wilk > Cc: linux-mips@xxxxxxxxxxxxxx; pebolle@xxxxxxxxxx; Zhang, Dongxing; > lauraa@xxxxxxxxxxxxxx; d.kasatkin@xxxxxxxxxxx; > heiko.carstens@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; ralf@linux- > mips.org; chris@xxxxxxxxxxxxxxxxxx; takahiro.akashi@xxxxxxxxxx; > david.vrabel@xxxxxxxxxx; linux@xxxxxxxxxxx; xen- > devel@xxxxxxxxxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx; Liu, Chuansheng; > akpm@xxxxxxxxxxxxxxxxxxxx > Subject: Re: [Xen-devel] [PATCH] modify the IO_TLB_SEGSIZE to > io_tlb_segsize configurable as flexible requirement about SW-IOMMU. > > On 06/02/15 00:10, Wang, Xiaoming wrote: > > > > > >> -----Original Message----- > >> From: Konrad Rzeszutek Wilk [mailto:konrad.wilk@xxxxxxxxxx] > >> Sent: Friday, February 6, 2015 3:33 AM > >> To: Wang, Xiaoming > >> Cc: ralf@xxxxxxxxxxxxxx; boris.ostrovsky@xxxxxxxxxx; > >> david.vrabel@xxxxxxxxxx; linux-mips@xxxxxxxxxxxxxx; linux- > >> kernel@xxxxxxxxxxxxxxx; xen-devel@xxxxxxxxxxxxxxxxxxxx; akpm@linux- > >> foundation.org; linux@xxxxxxxxxxx; lauraa@xxxxxxxxxxxxxx; > >> heiko.carstens@xxxxxxxxxx; d.kasatkin@xxxxxxxxxxx; > >> takahiro.akashi@xxxxxxxxxx; chris@xxxxxxxxxxxxxxxxxx; > >> pebolle@xxxxxxxxxx; Liu, Chuansheng; Zhang, Dongxing > >> Subject: Re: [PATCH] modify the IO_TLB_SEGSIZE to io_tlb_segsize > >> configurable as flexible requirement about SW-IOMMU. > >> > >> On Fri, Feb 06, 2015 at 07:01:14AM +0800, xiaomin1 wrote: > >>> The maximum of SW-IOMMU is limited to 2^11*128 = 256K. > >>> While in different platform and different requirements this seems > improper. > >>> So modify the IO_TLB_SEGSIZE to io_tlb_segsize as configurable is > >>> make > >> sense. > >> > >> More details please. What is the issue you are hitting? > >> > > Example: > > If 1M bytes are requied. There has an error like. > > Instead of allowing the bouncing of such large buffers, could the gadget > driver be modified to submit the buffers to the hardware in smaller chunks? > > David Our target is try to make IO_TLB_SEGSIZE configurable. Neither 256 bytes or 1M bytes seems suitable value, I think. It's better to use the tactics something like kmem_cache_create in kmalloc function. But SW-IOMMU seems more lighter. So we choose variable rather than function. Xiaoming.
