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DSPHLE: Add warning to use of MAIL_TERMINATE

This commit is contained in:
Pokechu22 2022-07-25 19:30:30 -07:00
parent e44b596f50
commit 1dcccb1f75
1 changed files with 24 additions and 1 deletions
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25
Source/Core/Core/HW/DSPHLE/UCodes/AESnd.cpp
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@ -161,7 +161,30 @@ void AESndUCode::HandleMail(u32 mail)
break;
case MAIL_TERMINATE:
INFO_LOG_FMT(DSPHLE, "AESndUCode - MAIL_TERMINATE: {:08x}", mail);
// This doesn't actually change the state of the system.
if (true) // currently no mainline libogc uCode has this issue fixed
{
// The relevant code looks like this:
//
// lrs $acc1.m,@CMBL
// ...
// cmpi $acc1.m,#0xdead
// jeq task_terminate
//
// The cmpi instruction always sign-extends, so it will compare $acc1 with 0xff'dead'0000.
// However, recv_cmd runs in set16 mode, so the load to $acc1 will produce 0x00'dead'0000.
// This means that the comparison never succeeds, and no mail is sent in response to
// MAIL_TERMINATE. This means that __dsp_donecallback is never called (since that's
// normally called in response to DSP_DONE), so __aesnddspinit is never cleared, so
// AESND_Reset never returns, resulting in a hang. We always send the mail to avoid this
// hang. (It's possible to exit without calling AESND_Reset, so most homebrew probably
// isn't affected by this bug in the first place.)
//
// A fix exists, but has not yet been added to mainline libogc:
// https://github.com/extremscorner/libogc2/commit/38edc9db93232faa612f680c91be1eb4d95dd1c6
WARN_LOG_FMT(DSPHLE, "AESndUCode - MAIL_TERMINATE is broken in this version of the "
"uCode; this will hang on real hardware or with DSP LLE");
}
// This doesn't actually change the state of the DSP code.
m_mail_handler.PushMail(DSP_DONE, true);
break;
default: