Date: Thu, 15 Jun 2006 17:08:09 -0400 From: John Baldwin <jhb@freebsd.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-hackers@freebsd.org Subject: Re: apic detection Message-ID: <200606151708.10218.jhb@freebsd.org> In-Reply-To: <4491A5BA.9060801@icyb.net.ua> References: <44903A53.9030007@icyb.net.ua> <200606151310.34246.jhb@freebsd.org> <4491A5BA.9060801@icyb.net.ua>
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On Thursday 15 June 2006 14:23, Andriy Gapon wrote: > on 15/06/2006 20:10 John Baldwin said the following: > > On Wednesday 14 June 2006 12:33, Andriy Gapon wrote: > >> What is proper way to check from a driver/module if APIC is being used ? > >> Or even narrower, if local APIC timer is being used ? > > > > There isn't currently. Why do you need to know? > > > > There is a driver that I am working on that could change frequency of > local APIC timer by changing FSB frequency and I want to make that > driver smarter and refuse to attach if local APIC timer is used. I know > that in 6.X and CURRENT local APIC timer is always used and in 5.X it is > never used, but I want my driver to handle environment more generally. It it always used if APIC is used. > I am thinking, can I just somehow check if IRQ0 is in use ? Would it be > something close to proper solution ? On x86 there is a variable called 'using_lapic_timer' that is available in sys/i386/isa/clock.c (and the amd64 equivalent), but I think it is static to that file, so you probably can't get to it. Other than that there really isn't a current way to know as the vast majority of the system does not (and should not) know or care. -- John Baldwin
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