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acpi, nfit: Remove ecc_unit_size

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The "Clear Error Unit" may be smaller than the ECC unit size on some
devices. For example, poison may be tracked at 64-byte alignment even
though the ECC unit is larger. Unless / until the ACPI specification
provides a non-ambiguous way to communicate this property do not expose
this to userspace.

Software that had been using this property must already be prepared for
the case where the property is not provided on older kernels, so it is
safe to remove this attribute.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2018-06-03 12:49:15 -07:00
parent d76401ade0
commit d4dd70915e
3 changed files with 17 additions and 30 deletions
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17
Documentation/ABI/removed/sysfs-bus-nfit Normal file
View file

@ -0,0 +1,17 @@
What: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size
Date: Aug, 2017
KernelVersion: v4.14 (Removed v4.18)
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Size of a write request to a DIMM that will not incur a
read-modify-write cycle at the memory controller.
When the nfit driver initializes it runs an ARS (Address Range
Scrub) operation across every pmem range. Part of that process
involves determining the ARS capabilities of a given address
range. One of the capabilities that is reported is the 'Clear
Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2
section 9.20.7.4 Function Index 1 - Query ARS Capabilities).
This property indicates the boundary at which the NVDIMM may
need to perform read-modify-write cycles to maintain ECC (Error
Correcting Code) blocks.

19
Documentation/ABI/testing/sysfs-bus-nfit
View file

@ -212,22 +212,3 @@ Description:
range. Used by NVDIMM Region Mapping Structure to uniquely refer
to this structure. Value of 0 is reserved and not used as an
index.
What: /sys/bus/nd/devices/regionX/nfit/ecc_unit_size
Date: Aug, 2017
KernelVersion: v4.14
Contact: linux-nvdimm@lists.01.org
Description:
(RO) Size of a write request to a DIMM that will not incur a
read-modify-write cycle at the memory controller.
When the nfit driver initializes it runs an ARS (Address Range
Scrub) operation across every pmem range. Part of that process
involves determining the ARS capabilities of a given address
range. One of the capabilities that is reported is the 'Clear
Uncorrectable Error Range Length Unit Size' (see: ACPI 6.2
section 9.20.7.4 Function Index 1 - Query ARS Capabilities).
This property indicates the boundary at which the NVDIMM may
need to perform read-modify-write cycles to maintain ECC (Error
Correcting Code) blocks.

11
drivers/acpi/nfit/core.c
View file

@ -1978,19 +1978,8 @@ static ssize_t range_index_show(struct device *dev,
}
static DEVICE_ATTR_RO(range_index);
static ssize_t ecc_unit_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct nd_region *nd_region = to_nd_region(dev);
struct nfit_spa *nfit_spa = nd_region_provider_data(nd_region);
return sprintf(buf, "%d\n", nfit_spa->clear_err_unit);
}
static DEVICE_ATTR_RO(ecc_unit_size);
static struct attribute *acpi_nfit_region_attributes[] = {
&dev_attr_range_index.attr,
&dev_attr_ecc_unit_size.attr,
NULL,
};