These docs are under active development and cover the v0.20 Kobicha security model.
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§11.4

Configuration Reference

Complete reference for all LCS self-configuration parameters. Every parameter lives under Machine\System\Registry\ and follows the self-configuration mechanism described in §8.2: compiled-in defaults at boot, hot-swapped via self-watch when registry values are available, validated against defined ranges, invalid values rejected with audit event.

All parameters are REG_DWORD (uint32). All have compiled-in defaults that produce correct behaviour without any registry configuration.

§11.4.1 Timeouts

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\RequestTimeoutMs 30000 1000 600000 milliseconds Per-request timeout for RSI operations, measured from first attempt to reserve an in-flight slot through response receipt. When exceeded, the calling thread receives ETIMEDOUT. The source stays alive. ETIMEDOUT
Machine\System\Registry\TransactionTimeoutMs 30000 1000 600000 milliseconds Maximum lifetime of an open transaction from reg_begin_transaction to auto-abort. Prevents stalled or malicious processes from holding the source's write lock indefinitely. Transaction auto-aborted; caller's next operation returns EINVAL.

§11.4.2 Path and naming limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxKeyDepth 512 32 4096 levels Maximum nesting depth for the key hierarchy. Bounds ancestor chain memory per fd and path resolution walk length. EINVAL on reg_open_key / reg_create_key
Machine\System\Registry\MaxPathComponentLength 255 64 1024 UTF-8 bytes Maximum length of a single key name component, value name, or layer name. ENAMETOOLONG
Machine\System\Registry\MaxTotalPathLength 16383 1024 65535 UTF-8 bytes Maximum total length of a full registry path including all components and separators. Matches or exceeds the Windows limit. ENAMETOOLONG
Machine\System\Registry\SymlinkDepthLimit 16 1 64 hops Maximum symlink resolution recursion depth during path resolution. ELOOP

§11.4.3 Value limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxValueSize 1048576 4096 67108864 bytes Maximum data payload size for a single value. Default 1 MB, ceiling 64 MB. ENOSPC

§11.4.4 Layer limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxLayersPerValue 128 1 1024 layers Maximum number of layers that can write to the same (key GUID, value name) pair. Bounds per-value layer resolution cost. ENOSPC
Machine\System\Registry\MaxTotalLayers 1024 16 65536 layers Maximum number of distinct layers in the in-memory layer table. Bounds kernel memory consumption from layer creation. ENOSPC on layer creation

§11.4.5 Transaction limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxBoundTransactionsPerSource 16 1 256 transactions Maximum number of concurrently bound (write-lock-holding) transactions per source. Prevents transaction chaining DoS. EBUSY on the operation that would bind the transaction
Machine\System\Registry\MaxReadOnlyTransactionsPerSource 16 1 256 transactions Maximum number of concurrently active read-only snapshot transactions per source, used by REG_IOC_BACKUP. Prevents backup snapshot DoS without treating backups as write-lock-holding transactions. EBUSY on REG_IOC_BACKUP

§11.4.6 Source limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxRegisteredSources 32 1 256 sources Maximum number of concurrently registered sources. ENOSPC on REG_SRC_REGISTER
Machine\System\Registry\MaxHivesPerSource 64 1 1024 hives Maximum number of hives a single source can register. ENOSPC on REG_SRC_REGISTER
Machine\System\Registry\MaxConcurrentRSIRequests 256 8 4096 requests Maximum simultaneously dispatched RSI requests awaiting response per source. When reached, new operations wait for a slot under the same RequestTimeoutMs deadline. Caller waits; ETIMEDOUT if no slot becomes available before the deadline.

§11.4.7 Watch limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\NotificationQueueSize 256 16 65536 events Maximum queued events per armed watch before overflow. When exceeded, oldest events are dropped and OVERFLOW is inserted. OVERFLOW event delivered to watcher.
Machine\System\Registry\MaxSubtreeWatchDepth 0 0 4096 levels Maximum depth from the watched key to descendant keys for subtree watch event delivery. 0 means unlimited (all descendants). Events for changes deeper than this limit are silently dropped. Events silently not delivered for changes beyond the depth limit.
Machine\System\Registry\MaxTransactionWatchEventBurst 4096 256 65536 events Maximum watch events generated per-watcher from a single transaction commit. When exceeded, LCS stops generating individual events and inserts a single OVERFLOW instead. OVERFLOW event delivered to watcher.

§11.4.8 Private hive and layer credential limits

Full path Default Min Max Unit Description Errno on violation
Machine\System\Registry\MaxScopeGUIDsPerToken 8 1 256 GUIDs Maximum private hive scope GUIDs a thread's credentials can carry. Bounds per-syscall routing iteration cost. Error at credential attachment time (KACS concern).
Machine\System\Registry\MaxPrivateLayersPerToken 16 1 256 layers Maximum private layer names a thread's credentials can carry. Bounds per-resolution is_active() iteration cost. Error at credential attachment time (KACS concern).

§11.4.9 Notes

  • All parameters are read from Machine\System\Registry\ via the self-watch mechanism. Changes take effect for new operations after the self-watch callback completes. In-flight operations use the value active when they started.

  • Invalid values (out of range, wrong type) are silently ignored. LCS retains the previous known-good value and emits an audit event.

  • Values are never clamped. The registry shows what was written; the audit log shows what LCS is actually using.

  • The SD on Machine\System\Registry\ controls who can modify these parameters. By default: SYSTEM and Administrators have KEY_ALL_ACCESS, Authenticated Users have KEY_READ. Domain policy via Group Policy at higher precedence layers provides additional protection.