Re: [GIT preview] for-6.3/cxl-ram-region

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Tue, 2023-01-31 at 19:46 +0000, Verma, Vishal L wrote:
> On Tue, 2023-01-31 at 14:03 -0500, Gregory Price wrote:
> > 
> > 
> > Right now I believe this is failing due to the interleave and size not
> > having default values
> > 
> > ./cxl create-region -m -t ram -d decoder0.0 -w 1 -g 4096 mem0
> > cxl region: create_region: create_region: unable to determine region size
> > cxl region: cmd_create_region: created 0 regions
> > 
> > 
> > appears to be due to this code
> > static int create_region(struct cxl_ctx *ctx, int *count,
> >              struct parsed_params *p)
> > {
> > // ... snip ...
> >     rc = create_region_validate_config(ctx, p);
> >     if (rc)
> >         return rc;
> > 
> >     if (p->size) {
> >         size = p->size;
> >         default_size = false;
> >     } else if (p->ep_min_size) {
> >         size = p->ep_min_size * p->ways;
> > **    } else {
> > **        log_err(&rl, "%s: unable to determine region size\n", __func__);
> > **        return -ENXIO;
> > **    }
> > 
> > So both size and ep_min_size are 0 here
> > 
> > echo region0 > /sys/bus/cxl/devices/decoder0.0/create_ram_region
> > cat /sys/bus/cxl/devices/region0/interleave_ways
> > 0
> > cat /sys/bus/cxl/devices/region0/interleave_granularity
> > 0
> > cat /sys/bus/cxl/devices/region0/size
> > 0
> 
> Ah - this revealed an actual bug in these commits - the size and
> ep_min_size don't refer to the region's size, it is the capacity of the
> component memdevs. Right after create_ram_region, the region size is
> expected to be zero.
> 
> However the bug here was a pmem assumption I had missed. When
> determining sizes, we only look at pmem capacity, which is wrong. It
> happened to work in my testing because the memdevs I used had both pmem
> and ram capacity. I'll update with a fix shortly. Thanks for trying it
> out and reporting this!

I've updated the branch now with a fix for this.