Date: Sat, 26 Sep 1998 19:10:43 +0900 From: Kazutaka YOKOTA <yokota@zodiac.mech.utsunomiya-u.ac.jp> To: freebsd-smp@FreeBSD.ORG Cc: jlemon@FreeBSD.ORG, yokota@zodiac.mech.utsunomiya-u.ac.jp Subject: VM86 on SMP Message-ID: <199809261010.TAA20805@zodiac.mech.utsunomiya-u.ac.jp>
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I compiled a SMP kernel with VM86.
It appears that the kernel panics as soon as something makes a vm86 call.
Example 1:
Enable apm0, then the kernel panics while apm0 is probed.
Trap 12
fault virtual address: 0xa00
fault code: superviser write
vm86_prepcall() at vm86_prepcall+0x4a
vm86_bioscall() at vm86_bioscall+0xe4
apmprobe() at apmprobe+0x3d
movl %eax,0(%edx,0) at vm86_prepcall+0x4a
Example 2:
Boot the kernel without APM, then try to load the VESA LKM.
The same panic at the same place.
vm86_prepcall() at vm86_prepcall+0x4a
vm86_bioscall() at vm86_bioscall+0xe4
But, this time it is the VESA LKM initialization routine which is
calling VM86.
The uniprocessor kernel has, of cource, no problems in the above
situations.
I think the fault is at the following line. We have a hardcoded
address here: 0xa00, Is this address valid in SMP?
vm86_prepcall(struct vm86frame vmf)
{
uintptr_t addr[] = { 0xA00, 0x1000 }; /* code, stack */
u_char intcall[] = {
CLI, INTn, 0x00, STI, HLT
};
if ((vmf.vmf_trapno & PAGE_MASK) <= 0xff) {
/*interrupt call requested */
intcall[2] = (u_char)(vmf.vmf_trapno & 0xff);
memcpy((void *)addr[0], (void *)intcall, sizeof(intcall));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
vmf.vmf_ip = addr[0];
vmf.vmf_cs = 0;
}
vmf.vmf_sp = addr[1] - 2; /* keep aligned */
vmf.kernel_es = vmf.kernel_ds = 0;
vmf.vmf_ss = 0;
vmf.vmf_eflags = PSL_VIF | PSL_VM | PSL_USER;
vm86_initflags(&vmf);
}
Kazu
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