Type 31: Boot Integrity Services Entry Point Guide

Boot Integrity Services entry-point addresses and structure validation.

Result set and ownership

lazybiosGetType31 returns a lazybiosType31Array_t holding every matching structure. Iterate entries using count. A non-NULL result whose count is zero means the table contains no structure of this type; NULL means the arguments were unusable or an allocation failed. Release the set with lazybiosFreeType31, or assign it to ctx->Type31 and let lazybiosCleanup own it.

Every record carries its own SMBIOS handle and the structure length the firmware reported.

Entry points

bis_entry_point_16 and bis_entry_point_32 contain the physical addresses of the 16-bit and 32-bit Boot Integrity Services entry points. A conforming structure has a formatted length of at least 1Ch and nonzero entry-point addresses.

Checksum

checksum contains the encoded structure-level checksum. When the complete formatted structure is available, checksum_valid is present and is nonzero only when the sum of every formatted byte evaluates to zero modulo 256. The parser preserves structures with invalid checksums so callers can inspect their raw fields.

Ownership

Release the returned array with lazybiosFreeType31, or assign it to lazybiosCTX::Type31 and use lazybiosCleanup.

See also

Type 31: Boot Integrity Services Entry Point