Changes between Initial Version and Version 1 of DeveloperHowToMigrate

Timestamp:

Jul 24, 2009, 3:16:58 PM (15 years ago)

Author:

Gabriele Pohl

Comment:

Insert content from old wiki

DeveloperHowToMigrate

@@ +1 @@
+[[PageOutline]]
+== Migrate old os_''youros''.cpp to new class interface ==
+
+Christian Franke wrote this quick outline how a migration works, which he already tested with os_linux.cpp.
+
+=== Step 1: Move adapter classes into os_''youros''.cpp ===
+
+ * Append adapter classes to old module:
+{{{
+#!sh
+$ cat dev_legacy.cpp >> os_youros.cpp
+[[code]]
+- Re-configure, this should now detect new interface:
+[[code format="bash"]]
+$ ./configure
+...
+checking whether os_youros.cpp uses new interface... yes
+}}}
+ * This should compile and work!
+ * Move #includes to top, remove duplicates.
+ * Remove all dummy functions for controllers not supported on your os (marvell_command_interface, ...).
+ * Remove corresponding classes (e.g legacy_marvell_device, ...).
+ * Remove corresponding section from legacy_smart_interface::get_custom_smart_device(). If nothing left, remove this function.
+ * Rename remaining classes 'legacy_*' to 'youros_*'. Rename namespace 'os' to 'os_youros'.
+ * This should compile and work!
+
+=== Step 2: Merge old functions into class member functions ===
+
+'''Old:'''
+{{{
+#!c
+int deviceopen(const char *pathname, char *type)
+{
+  ...
+  int fd = open(pathname, ...);
+  ...
+  return fd;
+}
+
+bool youros_smart_device::open()
+{
+  m_fd = ::deviceopen(get_dev_name(), (char*)m_mode);
+  if (m_fd < 0) {
+    set_err(errno);
+    return false;
+  }
+  return true;
+}
+}}}
+
+'''New:'''
+{{{
+#!cpp
+bool youros_smart_device::open()
+{
+  ...
+  m_fd = open(get_dev_name(), ...);
+  if (m_fd < 0) {
+    set_err(errno);
+    return false;
+  }
+  return true;
+}
+}}}
+
+'''Old:'''
+{{{
+#!c
+int ata_command_interface(int fd, smart_command_set command, int select, char *data)
+{
+  ...
+  if (ioctl(fd, ...))
+    return -1;
+  ...
+  return 0;
+}
+
+int youros_ata_device::ata_command_interface(smart_command_set command, int select, char * data)
+{
+  return ::ata_command_interface(get_fd(), command, select, data);
+}
+}}}
+
+'''New:'''
+{{{
+#!cpp
+int youros_ata_device::ata_command_interface(smart_command_set command, int select, char * data)
+{
+  ...
+  if (ioctl(get_fd(), ...))
+    return -1;
+  ...
+  return 0;
+}
+}}}
+
+
+=== Step 3: Convert SMART-only to full fledged ATA pass through ===
+
+ * Change base class of 'youros_ata_device' from 'ata_device_with_command_set' to 'ata_device'.
+ * Change 'youros_ata_device::ata_command_interface()' to 'youros_ata_device::ata_pass_through()'.
+ * Add parameter check using ata_cmd_is_ok(in, 'supported features')
+ * Remove 'switch (command) {....}', set ioctl input struct directly from input registers e.g. 'in.in_regs.*'.
+ * Remove special handling for SMART STATUS, return result registers in 'out.out_regs' if requested by 'in.out_needed.is_set()'.
+ * Adjust returns:
+{{{
+Replace 'return 0;' by 'return true;'.
+Replace 'errno = ERR; return -1;' by 'return set_err(ERR, "optional message", ...)'.
+}}}
+ * Optional add 48bit ATA pass through support:
+{{{
+If 'in.in_regs.is_48bit_cmd()' is set, 
+pass low (in.in_regs.lba_mid) and 
+high (in.in_regs.prev.lba_mid) byte of each register to ioctl.
+}}}
+
+=== Later ===
+ * Rework device scanning.
+ * Add/Rework auto-detection (function autodetect_open()).
+ * remove os_youros.h, each module does only export smart_interface::init().
+
+=== Example for Steps 1+2: ===
+http://smartmontools.cvs.sourceforge.net/viewvc/smartmontools/sm5/os_linux.cpp?r1=1.116&r2=1.117
+
+=== Example for Step 3 (3ware only): ===
+http://smartmontools.cvs.sourceforge.net/viewvc/smartmontools/sm5/os_linux.cpp?r1=1.117&r2=1.118