Hello,

This is the first of two patches to enable write barrier support (physical
disk cache flushing) on the Hurd. The corresponding userspace patch for
the Hurd repository (libstore, rumpdisk) will follow in a reply to this
thread.

This Mach change is a prerequisite for the userspace implementation.

device: Define DEV_FLUSH_CACHE status flavor

This defines the status flavor used by userspace translators to request
a physical write barrier from the device driver.

* include/device/device_types.h (DEV_FLUSH_CACHE): New macro.

Regards,
Milos
From c6f3bd9a8be46c4285fb8a13e7e5ce4a624e18b5 Mon Sep 17 00:00:00 2001
From: Milos Nikic <[email protected]>
Date: Fri, 23 Jan 2026 14:40:29 -0800
Subject: [PATCH] device: Define DEV_FLUSH_CACHE status flavor

define DEV_FLUSH_CACHE as 2.
This allows userspace translators to request a physical write barrier from the device driver.
---
 include/device/device_types.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/include/device/device_types.h b/include/device/device_types.h
index 583d9e0..bb74ba7 100644
--- a/include/device/device_types.h
+++ b/include/device/device_types.h
@@ -124,6 +124,8 @@ typedef int		dev_status_data_t[DEV_STATUS_MAX];
 #	define	DEV_GET_RECORDS_RECORD_SIZE	1	/* 1 if sequential */
 #define	DEV_GET_RECORDS_COUNT		2
 
+#define	DEV_FLUSH_CACHE		2
+
 /*
  * Device error codes
  */
-- 
2.52.0

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