gitformat-commit-graph: describe version 2 of BDAT

The code change to Git to support version 2 will be done in subsequent
commits.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/gitformat-commit-graph.txt b/Documentation/gitformat-commit-graph.txt
index 31cad585e233031d205e5338bed74fcaf125de1f..3e906e803096dfa4215034e36bd75150d2f871ad 100644 (file)
--- a/Documentation/gitformat-commit-graph.txt
+++ b/Documentation/gitformat-commit-graph.txt
@@ -142,13 +142,16 @@ All multi-byte numbers are in network byte order.
 
 ==== Bloom Filter Data (ID: {'B', 'D', 'A', 'T'}) [Optional]
     * It starts with header consisting of three unsigned 32-bit integers:
-      - Version of the hash algorithm being used. We currently only support
-       value 1 which corresponds to the 32-bit version of the murmur3 hash
+      - Version of the hash algorithm being used. We currently support
+       value 2 which corresponds to the 32-bit version of the murmur3 hash
        implemented exactly as described in
        https://en.wikipedia.org/wiki/MurmurHash#Algorithm and the double
        hashing technique using seed values 0x293ae76f and 0x7e646e2 as
        described in https://doi.org/10.1007/978-3-540-30494-4_26 "Bloom Filters
-       in Probabilistic Verification"
+       in Probabilistic Verification". Version 1 Bloom filters have a bug that appears
+       when char is signed and the repository has path names that have characters >=
+       0x80; Git supports reading and writing them, but this ability will be removed
+       in a future version of Git.
       - The number of times a path is hashed and hence the number of bit positions
              that cumulatively determine whether a file is present in the commit.
       - The minimum number of bits 'b' per entry in the Bloom filter. If the filter