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In order to better understand the mechanism, it’s worth looking at the individual messages as they are exchanged with IOS. Here’s what it might look like:
In order to better understand the mechanism, it’s worth looking at the individual messages as they are exchanged with IOS. Here’s what it might look like:
−PowerPCIOS
+ PowerPCIOS
−Initializing STM
+ Initializing STM
−open(path=”/dev/stm/immediate”)
+ open(path=”/dev/stm/immediate”)
−open() fd = 1
+ open() fd = 1
−open(path=”/dev/stm/eventhook”)
+ open(path=”/dev/stm/eventhook”)
−open() fd = 2
+ open() fd = 2
−ioctl(fd=2, num=EVENTHOOK, evbuf=0×12345600)
+ ioctl(fd=2, num=EVENTHOOK, evbuf=0×12345600)
−Time passes, user presses button
+ Time passes, user presses button
−Write event code to 0×12345600
+ Write event code to 0×12345600
−ioctl(fd=2) result = 0
+ ioctl(fd=2) result = 0
−Read event code from 0×12345600
+ Read event code from 0×12345600
−ioctl(fd=2, num=EVENTHOOK, evbuf=0×12345600)
+ ioctl(fd=2, num=EVENTHOOK, evbuf=0×12345600)
−Time passes, software decides to shut down STM
+ Time passes, software decides to shut down STM
−ioctl(fd=1, num=RELEASE)
+ ioctl(fd=1, num=RELEASE)
−Write 0 event code to 0×12345600
+ Write 0 event code to 0×12345600
−ioctl(fd=2) result = 0
+ ioctl(fd=2) result = 0
−ioctl(fd=1) result = 0
+ ioctl(fd=1) result = 0
−close(2)
+ close(2)
−close(2) result = 0
+ close(2) result = 0
−close(1)
+ close(1)
−close(1) result = 0
+ close(1) result = 0
Things didn’t work well when using the [[Twilight Hack]] because Zelda’s STM eventhook was still active, and STM won’t let you register a new one. So an STM eventhook release was added to the Twilight Hack. One slight issue is that we can’t know if there was an old eventhook or not, depending on what the state of the machine was (since the Twilight Hack can be relaunched from software, as an SD loader of sorts, and this was popular in the early days), so we just make it attempt to release the eventhook always. This is fine, as the release function will return an error if there is no eventhook active.
Things didn’t work well when using the [[Twilight Hack]] because Zelda’s STM eventhook was still active, and STM won’t let you register a new one. So an STM eventhook release was added to the Twilight Hack. One slight issue is that we can’t know if there was an old eventhook or not, depending on what the state of the machine was (since the Twilight Hack can be relaunched from software, as an SD loader of sorts, and this was popular in the early days), so we just make it attempt to release the eventhook always. This is fine, as the release function will return an error if there is no eventhook active.