[PATCHSET 0/5] User mapped provided buffer rings

Jens Axboe
2023-03-14T17:17:26Z

Hi,

One issue that became apparent when running io_uring code on parisc is
that for data shared between the application and the kernel, we must
ensure that it's placed correctly to avoid aliasing issues that render
it useless.

The first patch in this series is from Helge, and ensures that the
SQ/CQ rings are mapped appropriately. This makes io_uring actually work
there.

Patches 2..4 are prep patches for patch 5, which adds a variant of
ring mapped provided buffers that have the kernel allocate the memory
for them and the application mmap() it. This brings these mapped
buffers in line with how the SQ/CQ rings are managed too.

I'm not fully sure if this ONLY impacts archs that set SHM_COLOUR,
of which there is only parisc, or if SHMLBA setting archs (of which
there are others) are impact to any degree as well...

--
Jens Axboe