From 7c2c5ae72cab906dc1ae2f71e3620db9df984753 Mon Sep 17 00:00:00 2001
From: acevest <zhaoyanbai@126.com>
Date: Thu, 11 Nov 2021 14:29:51 +0800
Subject: [PATCH] =?utf8?q?fix=E5=9C=A8qemu=E4=B8=ADpci=20ide=20ata?=
 =?utf8?q?=E7=A1=AC=E7=9B=98DMA=E8=AF=BB=E4=B8=8D=E5=88=B0=E6=95=B0?=
 =?utf8?q?=E6=8D=AE=E7=9A=84=E9=97=AE=E9=A2=98?=
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---
 drivers/ide.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/ide.c b/drivers/ide.c
index d7ea5a2..fed4c4b 100644
--- a/drivers/ide.c
+++ b/drivers/ide.c
@@ -141,6 +141,15 @@ void ide_pci_init(pci_device_t *pci) {
     v = pci_read_config_word(pci_cmd(pci, PCI_COMMAND));
     printk(" ide pci command %04x\n", v);
 
+    // 这一句非常重要，如果不加这一句
+    // 在qemu中用DMA的方式读数据就会读不到数据，而只触是发中断，然后寄存器（Bus Master IDE Status
+    // Register）的值会一直是5 也就是INTERRUPT和和ACTIVE位是1，正常应该是4，也就是只有INTERRUPT位为1
+    // 在bochs中则加不加这一句不会有影响，都能正常读到数据
+    pci_write_config_word(v | PCI_COMMAND_MASTER, pci_cmd(pci, PCI_COMMAND));
+
+    v = pci_read_config_word(pci_cmd(pci, PCI_COMMAND));
+    printk(" ide pci command %04x\n", v);
+
     v = pci_read_config_byte(pci_cmd(pci, PCI_PROGIF));
     printk(" ide pci program interface %02x\n", v);
 
-- 
2.44.0