[PR] riscv: cpu: Check VLEN for RISCV_HWPROBE_IMA_V (PR #24231)

PR #24231 opened by CheryDan
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24231
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24231.patch

# Require 128-bit VLEN for `RISCV_HWPROBE_IMA_V`

Add the existing `VLEN >= 128` check to the `RISCV_HWPROBE_IMA_V` detection path, keeping it consistent with the Zve-based path.

This prevents RVV CPU flags from being enabled on systems with a smaller VLEN.



>From ad45932f5b6a0b556163b6c3887a4b04fc7ed453 Mon Sep 17 00:00:00 2001
From: daichengrong <[email protected]>
Date: Fri, 21 Aug 2026 17:55:19 +0800
Subject: [PATCH] riscv: cpu: Check VLEN for RISCV_HWPROBE_IMA_V

Require ff_get_rv_vlenb() >= 16 when detecting the V extension through
RISCV_HWPROBE_IMA_V, matching the existing Zve detection path.

This keeps the minimum 128-bit VLEN requirement consistent across both
hwprobe paths.

Signed-off-by: daichengrong <[email protected]>
---
 libavutil/riscv/cpu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavutil/riscv/cpu.c b/libavutil/riscv/cpu.c
index 481d63a39f..b1a2fc9c02 100644
--- a/libavutil/riscv/cpu.c
+++ b/libavutil/riscv/cpu.c
@@ -63,7 +63,8 @@ int ff_get_cpu_flags_riscv(void)
         if (pairs[0].value & RISCV_HWPROBE_BASE_BEHAVIOR_IMA)
             ret |= AV_CPU_FLAG_RVI;
 #ifdef RISCV_HWPROBE_IMA_V
-        if (pairs[1].value & RISCV_HWPROBE_IMA_V)
+        if ((pairs[1].value & RISCV_HWPROBE_IMA_V) &&
+                 ff_get_rv_vlenb() >= 16)
             ret |= AV_CPU_FLAG_RVV_I32 | AV_CPU_FLAG_RVV_I64
                  | AV_CPU_FLAG_RVV_F32 | AV_CPU_FLAG_RVV_F64;
 #ifdef RISCV_HWPROBE_EXT_ZVE32X
-- 
2.52.0

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