DOS ain't dead - UI21DEB deBUGGER released

UI21DEB deBUGGER released | inreentrant mess (Announce)

posted by ecm , Düsseldorf, Germany, 02.03.2009, 15:28

> > > Because your hook is inreentrant
> >
> > This would be a criminal BUG because it was supposed to be reentry-safe
> > :crying:
>
> Please calm down! "Will your TSR allow the debugger to single step into
> Int 21 without causing a mess?" was kind of a trick question. Correct
> answer is "No", but it's half of the truth only, the fully correct answer
> is "No, and I don't care at all, because it's your crappy debugger which
> is faulty" :-D

I rather expected this because of the question, but don't approve your intention. Well, yes, I probably won't ever use some program by DOS386, but I still prefer acceptable useless programs over crappy ones ;-)

> The reason is simple: your code clears IF, which is a hint for any
> debugger that a critical section is entered which isn't allowed to be
> interrupted. The problem is that all DEBUGs ignore this signal - they
> aren't designed to debug "low-level" code.

IF is often meaningless if any form of multitasking is running.

> You can make your code more tolerant by implementing Christian's
> stack frame solution, but it's probably not worth the effort.

The problem here is that even "normal" TSRs (not DEBUG) might want to use DOS functions reentrant in MS-DOS. Even the Int24 handler of COMMAND.COM might crash UI21DEB, because it (is allowed to and) calls some low functions (01h-0Ch) during another Int21 call.

---
l

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Complete thread:

UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 20.02.2009, 05:53 (Announce)
- UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 20.02.2009, 06:19
  - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - ecm, 20.02.2009, 20:19
    - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 24.02.2009, 06:02
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Laaca, 24.02.2009, 10:28
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - rr, 24.02.2009, 21:43
        UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - DOS386, 25.02.2009, 03:06
        UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - ecm, 25.02.2009, 13:15
      - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Japheth, 25.02.2009, 14:09
        UI21DEB deBUGGER released | the mess - DOS386, 01.03.2009, 08:24
        UI21DEB deBUGGER released | the mess - ecm, 01.03.2009, 10:40
        UI21DEB deBUGGER released | inreentrant mess - DOS386, 01.03.2009, 13:59
        UI21DEB deBUGGER released | inreentrant mess - ecm, 01.03.2009, 16:19
        UI21DEB deBUGGER released | inreentrant mess - Japheth, 02.03.2009, 07:48
        UI21DEB deBUGGER released | inreentrant mess - ecm, 02.03.2009, 15:28
        UI21DEB deBUGGER released | inreentrant mess - Japheth, 03.03.2009, 07:52
        UI21DEB deBUGGER released | crappy and incrappy stuff - DOS386, 15.03.2009, 02:39
        UI21DEB deBUGGER released | crappy and incrappy stuff - Japheth, 15.03.2009, 08:17
        UI21DEB deBUGGER released | crappy and incrappy stuff - ecm, 15.03.2009, 21:02
  - UI21DEB deBUGGER rele | DGJPP's persistent ENOENT bugginess - Laaca, 20.02.2009, 20:21