What: /sys/bus/platform/devices//mbwt///bandwidth Date: September 2026 KernelVersion: 7.4 Contact: Aniruddha TVS Rao Description: Provides access to Memory Bandwidth Throttler (MBWT) controls exposed by BPMP firmware for PCIe traffic and GPU traffic connected over the chip-to-chip link (NVCLINK) on the path to DRAM. The attributes are present only when BPMP firmware reports support for the MBWT GET_BW and SET_BW requests through the MBWT query ABI. Each directory identifies one PCIe bandwidth group. The available groups and their directory names are platform-specific. Current platforms use pcie0 through pcie5. Each bandwidth group has a single shared cap for all traffic in that group. A group may contain only PCIe devices, only a GPU connected over NVCLINK, or both PCIe and GPU traffic in a bifurcated topology. The directory selects the traffic type for the selected group. The following traffic types may be available: pcie_read PCIe read traffic pcie_write PCIe write traffic nvclink GPU traffic connected over NVCLINK Reading a bandwidth attribute returns the bandwidth cap in GB/s reported by firmware for that bandwidth group and traffic type. Writing an integer to a bandwidth attribute programs the target bandwidth cap in GB/s for that bandwidth group and traffic type. Examples: cat .../mbwt/pcie0/pcie_write/bandwidth echo 100 > .../mbwt/pcie0/pcie_write/bandwidth Users: Platform integration and bandwidth tuning on systems with BPMP firmware MBWT support.