Add ModeSense page 0x25 (DEC special function control page) (#1412)

* Add ModeSense page 0x25 (DECSpecialFunctionControlPage)

VAXServer 3100 (CPU KA41-E) console firmware issues ModeSense(6)
page 0x25 when probing for disks. A disk won't be recognized if
this returns an error.

The DEC SCSI specification[1], section 8.5 documents this page.

[1] https://manx-docs.org/collections/antonio/dec/dec-scsi.pdf

Fixes #1410

Signed-off-by: Klaus Kämpf <kkaempf@gmail.com>

cpp/devices/scsihd.cpp

@@ -97,8 +97,32 @@ void SCSIHD::AddFormatPage(map<int, vector<byte>>& pages, bool changeable) const
 	EnrichFormatPage(pages, changeable, 1 << GetSectorSizeShiftCount());
 }
 
+// Page code 37 (25h) - DEC Special Function Control page
+
+void SCSIHD::AddDECSpecialFunctionControlPage(map<int, vector<byte>>& pages, bool changeable) const
+{
+	vector<byte> buf(25);
+
+	// No changeable area
+	if (changeable) {
+		pages[0x25] = buf;
+
+		return;
+	}
+
+	buf[0] = static_cast<byte> (0x25 | 0x80); // page code, high bit set
+	buf[1] = static_cast<byte> (sizeof(buf) - 1);
+	buf[2] = static_cast<byte> (0x01); // drive does not auto-start
+
+	pages[0x25] = buf;
+}
+
 void SCSIHD::AddVendorPage(map<int, vector<byte>>& pages, int page, bool changeable) const
 {
+	// Page code 0x25: DEC Special Function Control page
+	if (page == 0x25 || page == 0x3f) {
+		AddDECSpecialFunctionControlPage(pages, changeable);
+	}
 	// Page code 48
 	if (page == 0x30 || page == 0x3f) {
 		AddAppleVendorModePage(pages, changeable);

cpp/devices/scsihd.h

@@ -40,6 +40,7 @@ public:
 	void ModeSelect(scsi_defs::scsi_command, cdb_t, span<const uint8_t>, int) override;
 
 	void AddFormatPage(map<int, vector<byte>>&, bool) const override;
+	void AddDECSpecialFunctionControlPage(map<int, vector<byte>>&, bool) const;
 	void AddVendorPage(map<int, vector<byte>>&, int, bool) const override;
 
 private:

cpp/test/mocks.h

@@ -360,6 +360,7 @@ class MockSCSIHD : public SCSIHD //NOSONAR Ignore inheritance hierarchy depth in
 	FRIEND_TEST(ScsiHdTest, FinalizeSetup);
 	FRIEND_TEST(ScsiHdTest, GetProductData);
 	FRIEND_TEST(ScsiHdTest, SetUpModePages);
+	FRIEND_TEST(ScsiHdTest, DECSpecialFunctionControlPage);
 	FRIEND_TEST(ScsiHdTest, GetSectorSizes);
 	FRIEND_TEST(ScsiHdTest, ModeSelect);
 	FRIEND_TEST(PiscsiExecutorTest, SetSectorSize);

cpp/test/scsihd_nec_test.cpp

@@ -18,11 +18,12 @@ using namespace filesystem;
 
 void ScsiHdNecTest_SetUpModePages(map<int, vector<byte>>& pages)
 {
-	EXPECT_EQ(5, pages.size()) << "Unexpected number of mode pages";
+	EXPECT_EQ(6, pages.size()) << "Unexpected number of mode pages";
 	EXPECT_EQ(12, pages[1].size());
 	EXPECT_EQ(24, pages[3].size());
 	EXPECT_EQ(20, pages[4].size());
 	EXPECT_EQ(12, pages[8].size());
+	EXPECT_EQ(25, pages[37].size());
 	EXPECT_EQ(30, pages[48].size());
 }
 

cpp/test/scsihd_test.cpp

@@ -13,11 +13,12 @@
 
 void ScsiHdTest_SetUpModePages(map<int, vector<byte>>& pages)
 {
-	EXPECT_EQ(5, pages.size()) << "Unexpected number of mode pages";
+	EXPECT_EQ(6, pages.size()) << "Unexpected number of mode pages";
 	EXPECT_EQ(12, pages[1].size());
 	EXPECT_EQ(24, pages[3].size());
 	EXPECT_EQ(24, pages[4].size());
 	EXPECT_EQ(12, pages[8].size());
+	EXPECT_EQ(25, pages[37].size());
 	EXPECT_EQ(30, pages[48].size());
 }
 
@@ -101,6 +102,20 @@ TEST(ScsiHdTest, SetUpModePages)
 	ScsiHdTest_SetUpModePages(pages);
 }
 
+TEST(ScsiHdTest, DECSpecialFunctionControlPage)
+{
+	map<int, vector<byte>> pages;
+	vector<byte> buf;
+	MockSCSIHD hd(0, false);
+
+	EXPECT_NO_THROW(hd.SetUpModePages(pages, 0x25, false)) << "MODE SENSE(6) DEC unique page is supported";
+	EXPECT_NE(pages.end(), pages.find(0x25));
+	buf = pages[0x25];
+	EXPECT_EQ(static_cast<byte> (0x25 | 0x80), buf[0]);
+	EXPECT_EQ(static_cast<byte> (0x17), buf[1]);
+	EXPECT_EQ(static_cast<byte> (0x01), buf[2]);
+}
+
 TEST(ScsiHdTest, ModeSelect)
 {
 	MockSCSIHD hd({ 512 });