Qualcomm Incorporated

Paul Kitchin

Adrian Montero

Huzefa Sanjeliwala

Conrado Blasco

Vikas Kumar Sinha

Pradeep Kanapathipillai

Prarthna Santhanakrishnan

Sunil Oak

Nir Maor

Henry Stracovsky

Antonio Priore

A method of explicit lockstep for functional safety includes spawning, by a main thread, a first safe thread core and a second safe thread core. The method also includes initializing and mapping a first data register associated with the first safe thread core to each safe variable of a set of predetermined safe variables. The method further includes initializing and mapping a second data register associated with the second safe thread core to each safe variable of the set of predetermined safe variables. The method also includes comparing, by a hardware comparator, a first safe variable value in the first data register to a second safe variable value in the second register. The method further includes issuing an error completion to the first safe thread core and the second safe thread core when the hardware comparator detects a mismatch between the first data register and the second data register.

Explicit lockstep for functional safety

Compressing translation lookaside buffer (TLB) tags using a TLB metadata buffer in processor-based devices is disclosed herein. In some aspects, a processor-based device provides a memory management unit (MMU) that includes a TLB and a TLB metadata buffer comprising a plurality of TLB metadata buffer entries storing corresponding TLB metadata. The MMU is configured to select a TLB metadata buffer entry for use in accessing the TLB of the processor-based device. After selecting the TLB metadata buffer entry, the MMU stores a pointer to the TLB metadata buffer entry as an active TLB metadata pointer. When the MMU subsequently receives a memory access request comprising a virtual address (VA), the MMU generates a TLB entry in the TLB for the VA, and stores the active TLB metadata pointer as part of the TLB tag of the TLB entry in lieu of the TLB metadata of the TLB metadata buffer entry.

Compressing translation lookaside buffer (TLB) tags using a TLB metadata buffer in processor-based devices

Filtering remote data synchronization barrier (DSB) instruction execution in processor-based devices is disclosed herein. In some exemplary aspects, a processor-based device provides a plurality of processors including an issuing processor and a remote processor. The remote processor receives, from the issuing processor, a translation lookaside buffer (TLB) invalidation (TLBI) instruction indicating a request to invalidate a TLB entry of a plurality of TLB entries of a TLB of the remote processor. The remote processor also receives a DSB instruction from the issuing processor. The remote processor determines whether the TLBI instruction satisfies filtering criteria, which specify conditions under which execution of the DSB instruction by the remote processor is unnecessary. If the remote processor determines that the TLBI instruction satisfies the filtering criteria, the remote processor foregoes execution of a DSB operation corresponding to the DSB instruction, and issues an early DSB acknowledgement to the issuing processor.

Filtering remote data synchronization barrier (DSB) instruction execution in processor-based devices

An electronic device includes one or more processors for executing one or more virtual machines. In response to a request for initiating a synchronization event, a processor identifies a subset of speculative memory access requests in one or more memory access request queues. Automatically and in accordance with the identifying, the processor purges translations associated with the subset of speculative memory access requests. Subsequent to the purging, the processor initiates the synchronization event. In some implementations, memory access completion is forced in response to a context synchronization event that corresponds to a termination of a first application, a termination of a first virtual machine, or a system call for updating a system register. Alternatively, in some implementations, memory access completion is forced in an operating system level or an application level in response to a data synchronization event that is initiated on a hypervisor layer or a firmware layer.

Latency management in synchronization events

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Austin, TX, United States of America

Paul Kitchin