On Thu, 2018-10-18 at 07:03 -0700, Matthew Wilcox wrote:
> On Thu, Oct 18, 2018 at 09:18:12PM +0800, Ming Lei wrote:
> > Filesystems may allocate io buffer from slab, and use this buffer to
> > submit bio. This way may break storage drivers if they have special
> > requirement on DMA alignment.
>
On Thu, Oct 18, 2018 at 08:06:05AM -0700, Matthew Wilcox wrote:
> Can you name one that does require 512-byte alignment, preferably still
> in use? Or even >4-byte alignment. I just checked AHCI and that requires
> only 2-byte alignment.
Xen-blkfront, rsxx, various SD/MMC card readers for
On Thu, Oct 18, 2018 at 04:05:51PM +0200, Christoph Hellwig wrote:
> On Thu, Oct 18, 2018 at 07:03:42AM -0700, Matthew Wilcox wrote:
> > Before we go down this road, could we have a discussion about what
> > hardware actually requires this? Storage has this weird assumption that
> > I/Os must be
On Thu, Oct 18, 2018 at 07:03:42AM -0700, Matthew Wilcox wrote:
> Before we go down this road, could we have a discussion about what
> hardware actually requires this? Storage has this weird assumption that
> I/Os must be at least 512 byte aligned in memory, and I don't know where
> this idea
On Thu, Oct 18, 2018 at 09:18:12PM +0800, Ming Lei wrote:
> Hi,
>
> Filesystems may allocate io buffer from slab, and use this buffer to
> submit bio. This way may break storage drivers if they have special
> requirement on DMA alignment.
Before we go down this road, could we have a discussion
Hi,
Filesystems may allocate io buffer from slab, and use this buffer to
submit bio. This way may break storage drivers if they have special
requirement on DMA alignment.
The patch 1 adds one warning if the io buffer isn't aligned to DMA
alignment.
The 2nd & 3rd patches make DMA alignment as
