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path: root/drivers/nvdimm/label.c
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2020-12-16libnvdimm/label: Return -ENXIO for no slot in __blk_label_updateZhang Qilong
Forget to set error code when nd_label_alloc_slot failed, and we add it to avoid overwritten error code. Fixes: 0ba1c634892b ("libnvdimm: write blk label set") Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com> Link: https://lore.kernel.org/r/20201205115056.2076523-1-zhangqilong3@huawei.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2020-11-20libnvdimm/namespace: Fix reaping of invalidated block-window-namespace labelsDan Williams
A recent change to ndctl to attempt to reconfigure namespaces in place uncovered a label accounting problem in block-window-type namespaces. The ndctl "create.sh" test is able to trigger this signature: WARNING: CPU: 34 PID: 9167 at drivers/nvdimm/label.c:1100 __blk_label_update+0x9a3/0xbc0 [libnvdimm] [..] RIP: 0010:__blk_label_update+0x9a3/0xbc0 [libnvdimm] [..] Call Trace: uuid_store+0x21b/0x2f0 [libnvdimm] kernfs_fop_write+0xcf/0x1c0 vfs_write+0xcc/0x380 ksys_write+0x68/0xe0 When allocated capacity for a namespace is renamed (new UUID) the labels with the old UUID need to be deleted. The ndctl behavior to always destroy namespaces on reconfiguration hid this problem. The immediate impact of this bug is limited since block-window-type namespaces only seem to exist in the specification and not in any shipping products. However, the label handling code is being reused for other technologies like CXL region labels, so there is a benefit to making sure both vertical labels sets (block-window) and horizontal label sets (pmem) have a functional reference implementation in libnvdimm. Fixes: c4703ce11c23 ("libnvdimm/namespace: Fix label tracking error") Cc: <stable@vger.kernel.org> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Ira Weiny <ira.weiny@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-09-05libnvdimm/label: Remove the dpa align checkAneesh Kumar K.V
There's no strict requirement why slot_valid() needs to check for page alignment and it would seem to actively hurt cross-page-size compatibility. Let's delete the check and rely on checksum validation. Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Link: https://lore.kernel.org/r/20190905154603.10349-6-aneesh.kumar@linux.ibm.com Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-06-05treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 295Thomas Gleixner
Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of version 2 of the gnu general public license as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 64 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190529141901.894819585@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-05-20libnvdimm: Fix compilation warnings with W=1Qian Cai
Several places (dimm_devs.c, core.c etc) include label.h but only label.c uses NSINDEX_SIGNATURE, so move its definition to label.c instead. In file included from drivers/nvdimm/dimm_devs.c:23: drivers/nvdimm/label.h:41:19: warning: 'NSINDEX_SIGNATURE' defined but not used [-Wunused-const-variable=] Also, some places abuse "/**" which is only reserved for the kernel-doc. drivers/nvdimm/bus.c:648: warning: cannot understand function prototype: 'struct attribute_group nd_device_attribute_group = ' drivers/nvdimm/bus.c:677: warning: cannot understand function prototype: 'struct attribute_group nd_numa_attribute_group = ' Those are just some member assignments for the "struct attribute_group" instances and it can't be expressed in the kernel-doc. Reviewed-by: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-04-30libnvdimm/namespace: Fix label tracking errorDan Williams
Users have reported intermittent occurrences of DIMM initialization failures due to duplicate allocations of address capacity detected in the labels, or errors of the form below, both have the same root cause. nd namespace1.4: failed to track label: 0 WARNING: CPU: 17 PID: 1381 at drivers/nvdimm/label.c:863 RIP: 0010:__pmem_label_update+0x56c/0x590 [libnvdimm] Call Trace: ? nd_pmem_namespace_label_update+0xd6/0x160 [libnvdimm] nd_pmem_namespace_label_update+0xd6/0x160 [libnvdimm] uuid_store+0x17e/0x190 [libnvdimm] kernfs_fop_write+0xf0/0x1a0 vfs_write+0xb7/0x1b0 ksys_write+0x57/0xd0 do_syscall_64+0x60/0x210 Unfortunately those reports were typically with a busy parallel namespace creation / destruction loop making it difficult to see the components of the bug. However, Jane provided a simple reproducer using the work-in-progress sub-section implementation. When ndctl is reconfiguring a namespace it may take an existing defunct / disabled namespace and reconfigure it with a new uuid and other parameters. Critically namespace_update_uuid() takes existing address resources and renames them for the new namespace to use / reconfigure as it sees fit. The bug is that this rename only happens in the resource tracking tree. Existing labels with the old uuid are not reaped leading to a scenario where multiple active labels reference the same span of address range. Teach namespace_update_uuid() to flag any references to the old uuid for reaping at the next label update attempt. Cc: <stable@vger.kernel.org> Fixes: bf9bccc14c05 ("libnvdimm: pmem label sets and namespace instantiation") Link: https://github.com/pmem/ndctl/issues/91 Reported-by: Jane Chu <jane.chu@oracle.com> Reported-by: Jeff Moyer <jmoyer@redhat.com> Reported-by: Erwin Tsaur <erwin.tsaur@oracle.com> Cc: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-02-02libnvdimm/dimm: Add a no-BLK quirk based on NVDIMM familyDan Williams
As Dexuan reports the NVDIMM_FAMILY_HYPERV platform is incompatible with the existing Linux namespace implementation because it uses NSLABEL_FLAG_LOCAL for x1-width PMEM interleave sets. Quirk it as an platform / DIMM that does not provide BLK-aperture access. Allow the libnvdimm core to assume no potential for aliasing. In case other implementations make the same mistake, provide a "noblk" module parameter to force-enable the quirk. Link: https://lkml.kernel.org/r/PU1P153MB0169977604493B82B662A01CBF920@PU1P153MB0169.APCP153.PROD.OUTLOOK.COM Reported-by: Dexuan Cui <decui@microsoft.com> Tested-by: Dexuan Cui <decui@microsoft.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2019-01-15libnvdimm/label: Clear 'updating' flag after label-set updateDan Williams
The UEFI 2.7 specification sets expectations that the 'updating' flag is eventually cleared. To date, the libnvdimm core has never adhered to that protocol. The policy of the core matches the policy of other multi-device info-block formats like MD-Software-RAID that expect administrator intervention on inconsistent info-blocks, not automatic invalidation. However, some pre-boot environments may unfortunately attempt to "clean up" the labels and invalidate a set when it fails to find at least one "non-updating" label in the set. Clear the updating flag after set updates to minimize the window of vulnerability to aggressive pre-boot environments. Ideally implementations would not write to the label area outside of creating namespaces. Note that this only minimizes the window, it does not close it as the system can still crash while clearing the flag and the set can be subsequently deleted / invalidated by the pre-boot environment. Fixes: f524bf271a5c ("libnvdimm: write pmem label set") Cc: <stable@vger.kernel.org> Cc: Kelly Couch <kelly.j.couch@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-12-10libnvdimm, label: Switch to bitmap_zalloc()Andy Shevchenko
Switch to bitmap_zalloc() to show clearly what we are allocating. Besides that it returns pointer of bitmap type instead of opaque void *. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Dave Jiang <dave.jiang@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12libnvdimm, label: Fix sparse warningDan Williams
The kbuild robot reports: drivers/nvdimm/label.c:500:32: warning: restricted __le32 degrades to integer ...read 'nslot' into a local u32. Reported-by: kbuild test robot <lkp@intel.com> Acked-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12nvdimm: Use namespace index data to reduce number of label reads neededAlexander Duyck
This patch adds logic that is meant to make use of the namespace index data to reduce the number of reads that are needed to initialize a given namespace. The general idea is that once we have enough data to validate the namespace index we do so and then proceed to fetch only those labels that are not listed as being "free". By doing this I am seeing a total time reduction from about 4-5 seconds to 2-3 seconds for 24 NVDIMM modules each with 128K of label config area. Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12nvdimm: Split label init out from the logic for getting config dataAlexander Duyck
This patch splits the initialization of the label data into two functions. One for doing the init, and another for reading the actual configuration data. The idea behind this is that by doing this we create a symmetry between the getting and setting of config data in that we have a function for both. In addition it will make it easier for us to identify the bits that are related to init versus the pieces that are a wrapper for reading data from the ACPI interface. So for example by splitting things out like this it becomes much more obvious that we were performing checks that weren't necessarily related to the set/get operations such as relying on ndd->data being present when the set and get ops should not care about a locally cached copy of the label area. Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12nvdimm: Remove empty if statementAlexander Duyck
This patch removes an empty statement from an if expression and promotes the else statement to the if expression with the expression logic reversed. I feel this is more readable as the empty statement can lead to issues if any additional logic was ever added. Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12nvdimm: Clarify comment in sizeof_namespace_indexAlexander Duyck
When working on the label code I found it rather confusing to see several spots that reference a minimum label size of 256 while working with labels that are 128 bytes in size. This patch is meant to provide a clarification on one of the comments that was at the heart of the issue. Specifically for version 1.2 and later of the namespace specification the minimum label size is 256, prior to that the minimum label size was 128. So we should state that as such to avoid confusion. Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-10-12nvdimm: Sanity check labeloffAlexander Duyck
This patch adds validation for the labeloff field in the indexes. Reviewed-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-03-15libnvdimm, label: change nvdimm_num_label_slots per UEFI 2.7Toshi Kani
sizeof_namespace_index() fails when NVDIMM devices have the minimum 1024 bytes label storage area. nvdimm_num_label_slots() returns 3 slots while the area is only big enough for 2 slots. Change nvdimm_num_label_slots() to calculate a number of label slots according to UEFI 2.7 spec. Signed-off-by: Toshi Kani <toshi.kani@hpe.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2018-03-06libnvdimm: remove redundant __func__ in dev_dbgDan Williams
Dynamic debug can be instructed to add the function name to the debug output using the +f switch, so there is no need for the libnvdimm modules to do it again. If a user decides to add the +f switch for libnvdimm's dynamic debug this results in double prints of the function name. Reported-by: Johannes Thumshirn <jthumshirn@suse.de> Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-09-28libnvdimm, namespace: fix label initialization to use valid seq numbersDan Williams
The set of valid sequence numbers is {1,2,3}. The specification indicates that an implementation should consider 0 a sign of a critical error: UEFI 2.7: 13.19 NVDIMM Label Protocol Software never writes the sequence number 00, so a correctly check-summed Index Block with this sequence number probably indicates a critical error. When software discovers this case it treats it as an invalid Index Block indication. While the expectation is that the invalid block is just thrown away, the Robustness Principle says we should fix this to make both sequence numbers valid. Fixes: f524bf271a5c ("libnvdimm: write pmem label set") Cc: <stable@vger.kernel.org> Reported-by: Juston Li <juston.li@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-08-29libnvdimm, label: fix index block size calculationDan Williams
The old calculation assumed that the label space was 128k and the label size is 128. With v1.2 labels where the label size is 256 this calculation will return zero. We are saved by the fact that the nsindex_size is always pre-initialized from a previous 128 byte assumption and we are lucky that the index sizes turn out the same. Fix this going forward in case we start encountering different geometries of label areas besides 128k. Since the label size can change from one call to the next, drop the caching of nsindex_size. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-07-03libnvdimm, namespace: record 'lbasize' for pmem namespacesDan Williams
Commit f979b13c3cc5 "libnvdimm, label: honor the lba size specified in v1.2 labels") neglected to update the 'lbasize' in the label when the namespace sector_size attribute was written. We need this value in the label for inter-OS / pre-OS compatibility. Fixes: f979b13c3cc5 ("libnvdimm, label: honor the lba size specified in v1.2 labels") Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-29libnvdimm, btt: BTT updates for UEFI 2.7 formatVishal Verma
The UEFI 2.7 specification defines an updated BTT metadata format, bumping the revision to 2.0. Add support for the new format, while retaining compatibility for the old 1.1 format. Cc: Toshi Kani <toshi.kani@hpe.com> Cc: Linda Knippers <linda.knippers@hpe.com> Cc: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: switch to using v1.2 labels by defaultDan Williams
The rules for which version of the label specification are in effect at any given point in time are as follows: 1/ If a DIMM has an existing / valid index block then the version specified is used regardless if it is a previous version. 2/ By default when the kernel is initializing new index blocks the latest specification version (v1.2 at time of writing) is used. 3/ An environment that wants to force create v1.1 label-sets must arrange for userspace to disable all active regions / namespaces / dimms and write a valid set of v1.1 index blocks to the dimms. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: add address abstraction identifiersDan Williams
Starting with v1.2 labels, 'address abstractions' can be hinted via an address abstraction id that implies an info-block format. The standard address abstraction in the specification is the v2 format of the Block-Translation-Table (BTT). Support for that is saved for a later patch, for now we add support for the Linux supported address abstractions BTT (v1), PFN, and DAX. The new 'holder_class' attribute for namespace devices is added for tooling to specify the 'abstraction_guid' to store in the namespace label. For v1.1 labels this field is undefined and any setting of 'holder_class' away from the default 'none' value will only have effect until the driver is unloaded. Setting 'holder_class' requires that whatever device tries to claim the namespace must be of the specified class. Cc: Vishal Verma <vishal.l.verma@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: add v1.2 label checksum supportDan Williams
The v1.2 namespace label specification adds a fletcher checksum to each label instance. Add generation and validation support for the new field. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: update 'nlabel' and 'position' handling for local namespacesDan Williams
The v1.2 namespace label specification requires 'nlabel' and 'position' to be valid for the first ("lowest dpa") label in the set. It also requires all non-first labels to set those fields to 0xff. Linux does not much care if these values are correct, because we can just trust the count of labels with the matching uuid like the v1.1 case. However, we set them correctly in case other environments care. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: populate 'isetcookie' for blk-aperture namespacesDan Williams
Starting with the v1.2 definition of namespace labels, the isetcookie field is populated and validated for blk-aperture namespaces. This adds some safety against inadvertent copying of namespace labels from one DIMM-device to another. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: populate the type_guid property for v1.2 namespacesDan Williams
The type_guid refers to the "Address Range Type GUID" for the region backing a namespace as defined the ACPI NFIT (NVDIMM Firmware Interface Table). This 'type' identifier specifies an access mechanism for the given namespace. This capability replaces the confusing usage of the 'NSLABEL_FLAG_LOCAL' flag to indicate a block-aperture-mode namespace. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: add v1.2 interleave-set-cookie algorithmDan Williams
The interleave-set-cookie algorithm is extended to incorporate all the same components that are used to generate an nvdimm unique-id. For backwards compatibility we still maintain the old v1.1 definition. Reported-by: Nicholas Moulin <nicholas.w.moulin@intel.com> Reported-by: Kaushik Kanetkar <kaushik.a.kanetkar@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2017-06-15libnvdimm, label: add v1.2 nvdimm label definitionsDan Williams
In support of improved interoperability between operating systems and pre-boot environments the Intel proposed NVDIMM Namespace Specification [1], has been adopted and modified to the the UEFI 2.7 NVDIMM Label Protocol [2]. Update the definitions of the namespace label data structures so that the new format can be supported alongside the existing label format. The new specification changes the default label size to 256 bytes, so everywhere that relied on sizeof(struct nd_namespace_label) must now use the sizeof_namespace_label() helper. There should be no functional differences from these changes as the default is still the v1.1 128-byte format. Future patches will move the default to the v1.2 definition. [1]: http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf [2]: http://www.uefi.org/sites/default/files/resources/UEFI_Spec_2_7.pdf Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-11-11nvdimm: use the right length of "pmem"Nicolas Iooss
In order to test that the name of a resource begins with "pmem", call strncmp() with 4 as length instead of 3 to match the whole prefix. Signed-off-by: Nicolas Iooss <nicolas.iooss_linux@m4x.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-10-07libnvdimm, namespace: update label implementation for multi-pmemDan Williams
Instead of assuming that there will only ever be one allocated range at the start of the region, account for additional namespaces that might start at an offset from the region base. After this change pmem namespaces now have a reason to carry an array of resources similar to blk. Unifying the resource tracking infrastructure in nd_namespace_common is a future cleanup candidate. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2016-09-30libnvdimm, label: convert label tracking to a linked listDan Williams
In preparation for enabling multiple namespaces per pmem region, convert the label tracking to use a linked list. In particular this will allow select_pmem_id() to move labels from the unvalidated state to the validated state. Currently we only track one validated set per-region. Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-25libnvdimm: infrastructure for btt devicesDan Williams
NVDIMM namespaces, in addition to accepting "struct bio" based requests, also have the capability to perform byte-aligned accesses. By default only the bio/block interface is used. However, if another driver can make effective use of the byte-aligned capability it can claim namespace interface and use the byte-aligned ->rw_bytes() interface. The BTT driver is the initial first consumer of this mechanism to allow adding atomic sector update semantics to a pmem or blk namespace. This patch is the sysfs infrastructure to allow configuring a BTT instance for a namespace. Enabling that BTT and performing i/o is in a subsequent patch. Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Neil Brown <neilb@suse.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-24libnvdimm: write blk label setDan Williams
After 'uuid', 'size', 'sector_size', and optionally 'alt_name' have been set to valid values the labels on the dimm can be updated. The difference with the pmem case is that blk namespaces are limited to one dimm and can cover discontiguous ranges in dpa space. Also, after allocating label slots, it is useful for userspace to know how many slots are left. Export this information in sysfs. Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Neil Brown <neilb@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-24libnvdimm: write pmem label setDan Williams
After 'uuid', 'size', and optionally 'alt_name' have been set to valid values the labels on the dimms can be updated. Write procedure is: 1/ Allocate and write new labels in the "next" index 2/ Free the old labels in the working copy 3/ Write the bitmap and the label space on the dimm 4/ Write the index to make the update valid Label ranges directly mirror the dpa resource values for the given label_id of the namespace. Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Neil Brown <neilb@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-24libnvdimm: pmem label sets and namespace instantiation.Dan Williams
A complete label set is a PMEM-label per-dimm per-interleave-set where all the UUIDs match and the interleave set cookie matches the hosting interleave set. Present sysfs attributes for manipulation of a PMEM-namespace's 'alt_name', 'uuid', and 'size' attributes. A later patch will make these settings persistent by writing back the label. Note that PMEM allocations grow forwards from the start of an interleave set (lowest dimm-physical-address (DPA)). BLK-namespaces that alias with a PMEM interleave set will grow allocations backward from the highest DPA. Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Neil Brown <neilb@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2015-06-24libnvdimm: namespace indices: read and validateDan Williams
This on media label format [1] consists of two index blocks followed by an array of labels. None of these structures are ever updated in place. A sequence number tracks the current active index and the next one to write, while labels are written to free slots. +------------+ | | | nsindex0 | | | +------------+ | | | nsindex1 | | | +------------+ | label0 | +------------+ | label1 | +------------+ | | ....nslot... | | +------------+ | labelN | +------------+ After reading valid labels, store the dpa ranges they claim into per-dimm resource trees. [1]: http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf Cc: Neil Brown <neilb@suse.de> Acked-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Dan Williams <dan.j.williams@intel.com>