From 874926800ff62bb8e21d5668500729a1956c5e66 Mon Sep 17 00:00:00 2001
From: Kawrakow <iwankawrakow@gmail.com>
Date: Thu, 13 Nov 2025 08:55:33 +0200
Subject: [PATCH] Add mainline compatible FA command line option (#944)

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
---
 common/common.cpp | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/common/common.cpp b/common/common.cpp
index 5d549d00..eddd5117 100644
--- a/common/common.cpp
+++ b/common/common.cpp
@@ -1135,6 +1135,21 @@ bool gpt_params_find_arg(int argc, char ** argv, const std::string & arg, gpt_pa
         params.flash_attn = false;
         return true;
     }
+    if (arg == "-fa" || arg == "--flash-attention") {
+        CHECK_ARG
+        std::string next_arg{argv[i]};
+        for (auto& c : next_arg) c = std::tolower(c);
+        if (next_arg == "auto" || next_arg == "1" || next_arg == "on") {
+            params.flash_attn = true;
+        }
+        else if (next_arg == "off" || next_arg == "0") {
+            params.flash_attn = false;
+        }
+        else {
+            invalid_param = true;
+        }
+        return true;
+    }
     if (arg == "-mla" || arg == "--mla-use") {
         CHECK_ARG
         params.mla_attn = std::stoi(argv[i]);
@@ -1981,6 +1996,7 @@ void gpt_params_print_usage(int /*argc*/, char ** argv, const gpt_params & param
     options.push_back({ "*",           "       --keep N",               "number of tokens to keep from the initial prompt (default: %d, -1 = all)", params.n_keep });
     options.push_back({ "*",           "       --chunks N",             "max number of chunks to process (default: %d, -1 = all)", params.n_chunks });
     options.push_back({ "*",           "-no-fa, --no-flash-attn",       "disable Flash Attention (default: %s)", params.flash_attn ? "enabled" : "disabled" });
+    options.push_back({ "*",           "-fa, --flash-attn (auto|on|off|0|1)", "set Flash Attention (default: %s)", params.flash_attn ? "on" : "off" });
     options.push_back({ "*",           "-mla,  --mla-use",              "enable MLA (default: %d)", params.mla_attn });
     options.push_back({ "*",           "-amb,  --attention-max-batch",  "max batch size for attention computations (default: %d)", params.attn_max_batch});
     options.push_back({ "*",           "-no-fmoe, --no-fused-moe",      "disable fused MoE (default: %s)", params.fused_moe_up_gate ? "enabled" : "disabled" });