mirror of
https://github.com/torvalds/linux.git
synced 2026-08-07 16:03:49 +02:00
779dd20cfb
CXL 2.0 allows for dynamic provisioning of new memory regions (system physical address resources like "System RAM" and "Persistent Memory"). Whereas DDR and PMEM resources are conveyed statically at boot, CXL allows for assembling and instantiating new regions from the available capacity of CXL memory expanders in the system. Sysfs with an "echo $region_name > $create_region_attribute" interface is chosen as the mechanism to initiate the provisioning process. This was chosen over ioctl() and netlink() to keep the configuration interface entirely in a pseudo-fs interface, and it was chosen over configfs since, aside from this one creation event, the interface is read-mostly. I.e. configfs supports cases where an object is designed to be provisioned each boot, like an iSCSI storage target, and CXL region creation is mostly for PMEM regions which are created usually once per-lifetime of a server instance. This is an improvement over nvdimm that pre-created "seed" devices that tended to confuse users looking to determine which devices are active and which are idle. Recall that the major change that CXL brings over previous persistent memory architectures is the ability to dynamically define new regions. Compare that to drivers like 'nfit' where the region configuration is statically defined by platform firmware. Regions are created as a child of a root decoder that encompasses an address space with constraints. When created through sysfs, the root decoder is explicit. When created from an LSA's region structure a root decoder will possibly need to be inferred by the driver. Upon region creation through sysfs, a vacant region is created with a unique name. Regions have a number of attributes that must be configured before the region can be bound to the driver where HDM decoder program is completed. An example of creating a new region: - Allocate a new region name: region=$(cat /sys/bus/cxl/devices/decoder0.0/create_pmem_region) - Create a new region by name: while region=$(cat /sys/bus/cxl/devices/decoder0.0/create_pmem_region) ! echo $region > /sys/bus/cxl/devices/decoder0.0/create_pmem_region do true; done - Region now exists in sysfs: stat -t /sys/bus/cxl/devices/decoder0.0/$region - Delete the region, and name: echo $region > /sys/bus/cxl/devices/decoder0.0/delete_region Signed-off-by: Ben Widawsky <bwidawsk@kernel.org> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Link: https://lore.kernel.org/r/165784333909.1758207.794374602146306032.stgit@dwillia2-xfh.jf.intel.com [djbw: simplify locking, reword changelog] Signed-off-by: Dan Williams <dan.j.williams@intel.com> |
||
|---|---|---|
| .. | ||
| 80211 | ||
| acpi | ||
| backlight | ||
| cxl | ||
| dmaengine | ||
| driver-model | ||
| early-userspace | ||
| firmware | ||
| fpga | ||
| gpio | ||
| hte | ||
| i3c | ||
| iio | ||
| md | ||
| media | ||
| mei | ||
| memory-devices | ||
| mmc | ||
| mtd | ||
| nfc | ||
| nvdimm | ||
| pci | ||
| phy | ||
| pldmfw | ||
| pm | ||
| rapidio | ||
| serial | ||
| soundwire | ||
| surface_aggregator | ||
| thermal | ||
| tty | ||
| usb | ||
| xilinx | ||
| auxiliary_bus.rst | ||
| basics.rst | ||
| clk.rst | ||
| component.rst | ||
| connector.rst | ||
| console.rst | ||
| dcdbas.rst | ||
| devfreq.rst | ||
| device_link.rst | ||
| device-io.rst | ||
| dma-buf.rst | ||
| edac.rst | ||
| eisa.rst | ||
| firewire.rst | ||
| frame-buffer.rst | ||
| generic-counter.rst | ||
| hsi.rst | ||
| i2c.rst | ||
| index.rst | ||
| infiniband.rst | ||
| infrastructure.rst | ||
| input.rst | ||
| interconnect.rst | ||
| io_ordering.rst | ||
| io-mapping.rst | ||
| ioctl.rst | ||
| ipmb.rst | ||
| ipmi.rst | ||
| isa.rst | ||
| isapnp.rst | ||
| libata.rst | ||
| mailbox.rst | ||
| men-chameleon-bus.rst | ||
| message-based.rst | ||
| misc_devices.rst | ||
| miscellaneous.rst | ||
| mtdnand.rst | ||
| ntb.rst | ||
| nvmem.rst | ||
| parport-lowlevel.rst | ||
| pin-control.rst | ||
| pps.rst | ||
| ptp.rst | ||
| pwm.rst | ||
| regulator.rst | ||
| reset.rst | ||
| rfkill.rst | ||
| s390-drivers.rst | ||
| scsi.rst | ||
| slimbus.rst | ||
| sm501.rst | ||
| spi.rst | ||
| switchtec.rst | ||
| sync_file.rst | ||
| target.rst | ||
| uio-howto.rst | ||
| vfio-mediated-device.rst | ||
| vfio-pci-device-specific-driver-acceptance.rst | ||
| vfio.rst | ||
| vme.rst | ||
| w1.rst | ||
| xillybus.rst | ||
| zorro.rst | ||