Difference between revisions of "Xbox 360 Backward Compatibility"
From xboxdevwiki
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=== Modifications to xboxkrnl.exe === | === Modifications to xboxkrnl.exe === | ||
| − | The | + | The IDEXPRDT section has been dropped, additionally the extra data from the MS-DOS header is gone. |
==== Guest to host communication ==== | ==== Guest to host communication ==== | ||
Revision as of 01:35, 30 May 2017
Xbox 360 Backward Compatibility is Microsofts original Xbox emulator for the Xbox 360.
The emulator binary is called xefu.xex. The first resource is xb1krnl which is a modified version of xboxkrnl.exe.
Modifications to xboxkrnl.exe
The IDEXPRDT section has been dropped, additionally the extra data from the MS-DOS header is gone.
Guest to host communication
The entrypoint of the kernel looks like:
80030878: 56 push %esi 80030879: 57 push %edi 8003087a: 8d 05 4c ac 02 80 lea 0x8002ac4c,%eax 80030880: 0f 3f (bad) 80030882: 04 20 80030884: 8d 05 6c ac 02 80 lea 0x8002ac6c,%eax 8003088a: 0f 3f (bad) 8003088c: 04 20 8003088e: 8d 05 8c ac 02 80 lea 0x8002ac8c,%eax 80030894: 0f 3f (bad) 80030896: 04 21 80030898: 8d 05 70 94 01 80 lea 0x80019470,%eax ...
According to this document by symantec (Page 5, Left-hand-side) the patterns 0F 3F x1 x2 and 0F C7 C8 y1 y2 are used for communication with the host.
| x1 | x2 | Notes |
|---|---|---|
| 0x04 | 0x20 | Seems to use eax (address) as parameter? eax points to a zero terminated list of pointers into the kernel memory [7 elements] |
| 0x04 | 0x21 | Seems to use eax (address) as parameter? " [4 elements] |
| 0x04 | 0x22 | Seems to use eax (address) as parameter? Seems to be some call to that address?! |
| 0x04 | 0x23 | Seems to use eax (address) as parameter? |
| 0x04 | 0x24 | Seems to use eax (address) as parameter? |
| 0x04 | 0x35 | Seems to use eax (address) as parameter? |
| 0x04 | 0x50 | Seems to use eax (address) as parameter? " [3 elements] |
| Cleaner list starts here [FIXME] | ||
| 0x04 | 0x20 | |
| 0x04 | 0x20 | |
| 0x04 | 0x21 | |
| 0x04 | 0x22 | |
| 0x04 | 0x23 | |
| 0x04 | 0x24 | |
| 0x04 | 0x35 | |
| 0x04 | 0x50 | |
| 0x06 | 0x00 | Seems to use eax (address) and ecx (size) as parameter? Memory is 0x00 filled before. location is 0x8002b420, size would be 0x3000 |
| 0x06 | 0x02 | |
| 0x06 | 0x20 | Some call or callback registration to the address pointed to by eax |
| 0x06 | 0x21 | |
| 0x06 | 0x22 | |
| 0x06 | 0x23 | Some call or callback registration to the address pointed to by eax |
| 0x06 | 0x24 | |
| 0x06 | 0x25 | |
| 0x06 | 0x26 | |
| 0x06 | 0x27 | |
| 0x06 | 0x28 | |
| 0x06 | 0x29 | |
| 0x06 | 0x40 | |
