Berkeley Packet Filter—the original bytecode format used for Solana programs, inherited from Linux's eBPF. Programs written in Rust or C are compiled to BPF bytecode and executed in a sandboxed VM. BPF has been superseded by SBF on Solana but the tooling names (BPF Loader, cargo build-bpf) persist for historical reasons.
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Berkeley Packet Filter—the original bytecode format used for Solana programs, inherited from Linux's eBPF. Programs written in Rust or C are compiled to BPF bytecode and executed in a sandboxed VM. BPF has been superseded by SBF on Solana but the tooling names (BPF Loader, cargo build-bpf) persist for historical reasons.
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Think of it as part of the chain machinery that keeps ordering, execution, or consensus moving.
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Consensus, leader rotation, slots, epochs, and the runtime.
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BPF (Berkeley Packet Filter) (bpf) Category: Core Protocol Definition: Berkeley Packet Filter—the original bytecode format used for Solana programs, inherited from Linux's eBPF. Programs written in Rust or C are compiled to BPF bytecode and executed in a sandboxed VM. BPF has been superseded by SBF on Solana but the tooling names (BPF Loader, cargo build-bpf) persist for historical reasons. Aliases: BPF, eBPF Related: SBF (Solana Bytecode Format), Solana Virtual Machine (SVM)
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Solana Bytecode Format—Solana's customized evolution of BPF. SBF adds Solana-specific syscalls, modifies calling conventions, disables certain eBPF instructions, and adds features like position-independent code. Programs are compiled with `cargo build-sbf` and deployed as SBF ELF binaries. SBF replaced BPF as the canonical bytecode format.
The Solana Virtual Machine—the execution environment that runs on-chain programs. SVM loads SBF bytecode, provides syscalls for account access and cryptographic operations, enforces compute budgets, and manages memory. The SVM is being modularized (via the SVM API) to enable use in rollups and other environments outside the main Solana validator.
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An initiative to migrate Solana's native programs (System Program, Stake Program, Vote Program, and others currently compiled into the validator binary) to BPF/SBF bytecode deployed on-chain. This migration enables these core programs to be upgraded via feature gates and governance without requiring validator software releases, improving protocol agility. The programs maintain the same addresses and interfaces while gaining the upgradeability of standard on-chain programs.
Glossary entries become useful when they are connected. These links are the shortest path to adjacent ideas.
Solana Bytecode Format—Solana's customized evolution of BPF. SBF adds Solana-specific syscalls, modifies calling conventions, disables certain eBPF instructions, and adds features like position-independent code. Programs are compiled with `cargo build-sbf` and deployed as SBF ELF binaries. SBF replaced BPF as the canonical bytecode format.
The Solana Virtual Machine—the execution environment that runs on-chain programs. SVM loads SBF bytecode, provides syscalls for account access and cryptographic operations, enforces compute budgets, and manages memory. The SVM is being modularized (via the SVM API) to enable use in rollups and other environments outside the main Solana validator.
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A clock mechanism that cryptographically proves the passage of time between events. PoH uses a sequential SHA-256 hash chain where each output becomes the next input, creating a verifiable ordering of events without requiring consensus. The leader produces ~400,000 hashes per slot (~400ms), and any validator can verify the sequence in parallel, enabling Solana's high throughput by removing the need for validators to agree on time.
Solana's custom BFT consensus algorithm built on top of Proof of History. Tower BFT uses PoH as a clock to reduce communication overhead in traditional PBFT from O(n²) to O(n). Validators vote on forks with exponentially increasing lockout periods—each consecutive vote doubles the lockout, making rollbacks progressively more expensive. A fork is finalized when it reaches supermajority (66.7%+ of stake).
A time window during which a designated leader validator can produce a block. Each slot lasts approximately 400 milliseconds. Slots are numbered sequentially from genesis and grouped into epochs of 432,000 slots (~2-3 days). Not every slot produces a block—a skipped slot means the leader was offline or too slow.
A set of entries produced by a leader during a single slot. A block contains transactions bundled into entries, each with a PoH hash proving ordering. Blocks are broken into shreds for network propagation via Turbine. Maximum block size is limited by compute units (48M CU cap per block) rather than byte size.