Date: Thu, 02 Oct 2003 14:57:03 +0200 From: Grumble <invalid@kma.eu.org> To: freebsd-hackers@freebsd.org Subject: Re: Why is PCE not set in CR4? Message-ID: <3F7C209F.7000205@kma.eu.org>
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>>> I have read the perfmon documentation and source code. For several >>> reasons, I do not think it is totally adequate in my situation. >> >> This is an extension to the i386_vm86() syscall which will let you turn >> PCE on and off if you're the superuser. > > Now that I think on this a bit more, a sysctl might be a better place to > put this, but it seemed to belong with the i386_vm86() bits, rather than > polluting initcpu.c right away. Is vm86 related to virtual-8086 mode? Probably not... What does vm86 stand for? Virtual machine? > Mind you, if you're going to hack perfmon, perhaps putting this in initcpu > isn't such a bad idea after all, with a loader tunable instead. That way > perfmon can pickup on the tunable when attached by nexus during boot. I am tempted to remove perfmon from the kernel, and write a kernel module for Athlon and another one for NetBurst. Can a kernel module catch #UD (Invalid Opcode) and #GP (General Protection) exceptions generated from within the kernel module itself? Can I use sigaction(2)? Can a kernel module catch a specific #GP exception generated from user land? Can I register a signal handler with sigaction(2)? BTW, are performance-monitoring counters saved and restored on a context switch? Shill
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