View source for LimHD:EXT2

== ext2 ==

Since I only use OsX at home, and do not really use Windows, it does not make much sense to use '''NTFS''' on the internal HDD. The Linux kernel has '''ext2''' support, and since the limits of '''ext2''' are quite acceptable [http://en.wikipedia.org/wiki/Ext2#File_system_limits] I formatted it ext2 with block size of '''2048'''.

As it turns out, I actually had a lot of other problems, in that the HDD stops working after being on for about 10 minutes. Usually with "lost interrupt", "resetting MBUS" messages. Either the HDD is bad and dying, or my '''LimHD200i''' is bad. Either way, since I want a writable HDD, and run FTP and SMB, '''ext2''' makes much more sense.


But, '''curacao''' does not recognise '''ext2''' on the internal HDD. Only '''vfat''' and '''ntfs'''. The check for that is located here:


 xseg000:000568A4 loc_568A4                               ; CODE XREF: print_mounted+C8vj                                                     
 xseg000:000568A4                 MOV     R0, R7          ; loops here until R5 is 10                                                         
 xseg000:000568A8                 LDR     R1, =aDevIdeHost0Bus ; Load from Memory                                                             
 xseg000:000568AC                 MOV     R2, R5          ; Rd = Op2                                                                          
 xseg000:000568B0                 BL      sprintf_2A3314  ; R1 = /dev/ide/%R5 (R2)                                                            
 xseg000:000568B4                 MOV     R0, R6          ; R6 = /dev/ide/host%d                                                              
 xseg000:000568B8                 LDR     R1, =aMntHdD    ; Load from Memory                                                                  
 xseg000:000568BC                 MOV     R2, R5          ; Rd = Op2                                                                          
 xseg000:000568C0                 BL      sprintf_2A3314  ; /mnt/HD%R5                                                                        
 xseg000:000568C4                 LDR     R3, =aIocharsetUtf8_0 ; Load from Memory                                                            
 xseg000:000568C8                 STR     R3, [SP,#0x88+var_88] ; Store to Memory                                                             
 xseg000:000568CC                 MOV     R0, R7          ; Rd = Op2                                                                          
 xseg000:000568D0                 MOV     R1, R6          ; Rd = Op2                                                                          
 xseg000:000568D4                 LDR     R2, =aVfat_0    ; Load from Memory                                                                  
 xseg000:000568D8                 MOV     R3, #7          ; Rd = Op2                                                                          
 xseg000:000568DC                 BL      testfstype_2A9E1C ; Branch with Link                                                                
 xseg000:000568E0                 CMP     R0, #0          ; Set cond. codes on Op1 - Op2                                                      
 xseg000:000568E4                 BEQ     loc_5690C       ; Branch                                                                            
 xseg000:000568E8                 LDR     R3, =aNlsUtf8   ; Load from Memory                                                                  
 xseg000:000568EC                 STR     R3, [SP,#0x88+var_88] ; Store to Memory                                                             
 xseg000:000568F0                 SUB     R0, R11, #0x60  ; Rd = Op1 - Op2                                                                    
 xseg000:000568F4                 SUB     R1, R11, #0x80  ; Rd = Op1 - Op2                                                                    
 xseg000:000568F8                 LDR     R2, =aNtfs_0    ; Load from Memory                                                                  
 xseg000:000568FC                 MOV     R3, #7          ; Rd = Op2                                                                          
 xseg000:00056900                 BL      testfstype_2A9E1C ; Branch with Link                                                                
 xseg000:00056904                 CMP     R0, #0          ; Set cond. codes on Op1 - Op2                                                      
 xseg000:00056908                 BNE     loc_56934       ; Branch                                                                             

In binary
 00056910: 0610 a0e1 9020 9fe5 '''07'''30 a0e3 4e4d 09eb  ..... ...0..NM..
 00056920: 0000 50e3 0800 000a 8030 9fe5 0030 8de5  ..P......0...0..
 00056930: 6000 4be2 8010 4be2 7420 9fe5 '''07'''30 a0e3  `.K...K.t ...0..


Basically, it uses mount flags '''#7''' which is '''READONLY NOSUID NODEV''', tries to mount it with type '''vfat''' and mount options '''iocharset=utf8'''. If that fails, it tries '''#7''' with '''ntfs''' and '''nls=utf8'''. Changing '''ntfs''' to '''ext2''' will result in:

 EXT2-fs: Unrecognized mount option nls=utf8

So, we need to replace the mount option '''nls=utf8''' as well. According to '''linux-2.4.22-em86xx/fs/ext2/super.c''' we can chose from:

 bsddf nouid32 check debug errors=continue/remount-ro/panic) grpid bsdgroups minixdf nocheck nogrpid sysvgroups resgid resuid sb grpquota noquota quota usrquota

I went with '''nocheck''' for now. There are a few in there that would be relatively harmless.

So basically, I have decided to change '''vfat''' to '''ext2''' so that you can still mount '''ntfs''' as well as '''ext2'''.  I have changed the first '''#7''' to '''#6''' to make '''ext2''' mount in '''read-write''' mode.


=== Restarting curacao ===


The next problem is restarting '''curacao'''. It needs to be shut down in such a way that we can open '''/dev/ir''' again, which is only allowed to be opened once.

First you kill the '''curacao''' process, usually the lowest pid. Then you should kill all the '''udhcpc''' processes, (I used highest pid to lowest order, does this matter?) and if you ran '''cat /proc/kmsg &''' before then, you should get this message:

 <7>ir: Disable NEC decoder
 <7>ir: Disable RC5 decoder
 <7>ir: Disable RC6 decoder

Sweet, now you can start '''curacao''' again, I use Samba mount.

 '''/mnt/smbfs/curacao-ext2 /mnt /dev/ir'''

I can not provide the patched binary of '''curacao''' sorry, but go here [[LimHD:Firmware|Firmware]]

Naturally, eventually I will roll my own firmware with my version of '''curacao''' but you really want to make sure it works before you do that, since without a working '''curacao''' you '''can not flash a new firmware!'''. This is why I did it this way for now.

I also need to compile '''e2fsck''' and run it at boot. Maybe even '''mke2fs''' because I am nice.

I have compiled a version of busybox with '''fdisk''', '''e2fsck''' and '''mkfs.ext2''' so that simple ext2 setup can be performed. I have thus made my HDD have partition 1 as '''ntfs''' and partition 2 as '''ext2''' so that I can keep testing my code against both. '''curacao''' mounts both.

=== read-only ===

 /dev/ide/host0/bus0/target0/lun0/part1 on /mnt/HD1 type ext2 (ro,nosuid)

Alas, it is mounted '''read-only'''. I need to find this option next.

 #define MS_RDONLY    1      /* Mount read-only */
 #define MS_NOSUID    2      /* Ignore suid and sgid bits */

So, most likely there is a '''3''' somewhere (actually, it is '''7''', as seen above) . Definitely in '''R3'''.


 /dev/ide/host0/bus0/target0/lun0/part1    39.1G      4.3G     34.8G  11% /mnt/HD1
 /dev/ide/host0/bus0/target0/lun0/part2   111.8G     18.0M    106.1G   0% /mnt/HD2


In retrospect, mounting the HDD in read/write isn't a great idea. Since this device needs plenty of reboots, and you can not do that cleanly. I have '''fsck''' but it needs a huge amount of memory. If you kill everything, '''curacao''', smbmount etc, I could '''just''' run it. That's on a 100Gb partition, so not very nice. Seriously, you will need '''swap''' partition. So I will go back to read-only, and use '''FTP SITE MOUNT''' to make it read/write temporarily.