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blog:pushbx:2022:0424_ldebugx_compatibility_tweaks_dosemu2_native_dpmi_bugfix

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blog:pushbx:2022:0424_ldebugx_compatibility_tweaks_dosemu2_native_dpmi_bugfix [2022-04-24 14:35:32 +0200 Apr Sun] (current)
ecm created
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 +====== lDebugX compatibility tweaks, dosemu2 native DPMI bugfix ======
 +
 +After [[https://github.com/dosemu2/dosemu2/discussions/1609|some discussion]] on lDebugX
 +running a DPMI client in dosemu2
 +on a hosteurope virtual server,
 +several changes were made to both
 +lDebugX and dosemu2.
 +dosemu2 got [[https://github.com/dosemu2/dosemu2/issues/1615|a genuine bugfix]]
 +out of this. Or [[https://github.com/dosemu2/dosemu2/issues/1620|two]].
 +Or [[https://github.com/dosemu2/dosemu2/issues/1616|three]].
 +
 +===== =====
 +
 +lDebugX changes include:
 +
 +  * [[https://hg.pushbx.org/ecm/ldebug/rev/8b922d9f2d4e|zeroing a field in the 86M register structure]]
 +
 +  * [[https://hg.pushbx.org/ecm/ldebug/rev/2ceb9080a25e|option to set B bit of debugger's stack segment]] (run on a 32-bit stack, albeit still in the low 64 KiB)
 +
 +  * [[https://hg.pushbx.org/ecm/ldebug/rev/3964726454c4|some general hardening for esp use]]
 +
 +  * [[https://hg.pushbx.org/ecm/ldebug/rev/ddef2af434b9|option to break into the debugger upon entering Protected Mode]]
 +
 +This last one is mostly a convenience really.
 +It does open up an interesting possibility
 +when debugging lDDebugX using lDebugX:
 +if the outer lDebugX sets the option,
 +it will gain control when the inner
 +lDDebugX's ''installdpmi'' handler
 +starts executing.
 +However, as the debuggee is technically running
 +in lDDebugX's client context here,
 +the debuggable debugger will set up
 +its own PM handlers.
 +That means that the outer lDebugX
 +cannot safely trace past
 +[[https://hg.pushbx.org/ecm/ldebug/file/3e124d82e507/source/pminit.asm#l365|the point at which lDDebugX's exception handlers are installed]].
 +
 +
 +
 +{{tag>ldebug dpmi dosemu2 bugfix}}
 +
 +
 +~~DISCUSSION~~
  
blog/pushbx/2022/0424_ldebugx_compatibility_tweaks_dosemu2_native_dpmi_bugfix.txt ยท Last modified: 2022-04-24 14:35:32 +0200 Apr Sun by ecm