Date: Mon, 19 Jan 1998 20:17:59 -0500 From: Randall Hopper <rhh@ct.picker.com> To: Jonathan Lemon <jlemon@americantv.com> Cc: emulation@FreeBSD.ORG Subject: Re: DOSCMD: Problems w/ Quicken Message-ID: <19980119201759.61620@ct.picker.com> In-Reply-To: <19980119103920.28769@right.PCS>; from Jonathan Lemon on Mon, Jan 19, 1998 at 10:39:20AM -0600 References: <19980119022348.44312@hydrogen.nike.efn.org> <199801191136.WAA00350@word.smith.net.au> <19980119103920.28769@right.PCS>
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Jonathan Lemon:
|>From one of the original postings, the setup message for doscmd says
|`Init: 0', which indicates that the hardware does not support VME.
Hmm. Well, in the boot-up probes, it says my CPU does support VME:
CPU: Pentium (233.22-MHz 586-class CPU)
Origin = "GenuineIntel" Id = 0x543 Stepping=3
Features=0x8001bf<FPU,VME,DE,PSE,TSC,MSR,MCE,CX8,MMX>
However, looking at the sysarch() kernel path briefly, it appears that the
0 after Init: is just the return code of sysarch() and vm86_sysarch(),
which for the latter, just implies that the copyin()'s and
i386_extend_pcb() didn't fail.
|When an int13 (gpf) is generated, under VME, it simply looks at the
|interrupt vector, and jumps directly to the associated interrupt handler,
|without leaving vm86 mode. Without VME, it falls back to doscmd, with
|a SIGBUS.
|
|doscmd looks at the instruction to try to figure out why the interrupt
|was generated (sti, cli, popf, etc) and if it doesn't find it, assumes
|that this is an illegal instruction. It doesn't attempt to jump to the
|int 13 vector. It does this since SIGBUS is overloaded with all sorts
|of things and typically a GPF is fatal anyway.
|
|The following (untested) patch to doscmd might fix the problem.
|--
|+ #if 0
| dump_regs(REGS);
| fatal("unsupported instruction\n");
|+ #endif
|+ fake_int(REGS, 13);
I just tried this, but when the exception happened, I got an unending
stream of:
IRQ5 with no handler!
IRQ5 with no handler!
in the parent terminal. I don't know if this is a result or just the next
snag after the current one.
Randall
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