Date: Tue, 20 May 2008 11:24:23 -0400 From: John Baldwin <jhb@freebsd.org> To: Andriy Gapon <avg@icyb.net.ua> Cc: freebsd-hackers@freebsd.org, RW <fbsd06@mlists.homeunix.com> Subject: Re: i386 cpu_reset_real: code/comment mismatch Message-ID: <200805201124.23850.jhb@freebsd.org> In-Reply-To: <4832D432.2050907@icyb.net.ua> References: <1210616585.00069210.1210605002@10.7.7.3> <1211246591.00072455.1211234402@10.7.7.3> <4832D432.2050907@icyb.net.ua>
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On Tuesday 20 May 2008 09:37:54 am Andriy Gapon wrote: > on 20/05/2008 00:51 John Baldwin said the following: > > So, the comment is correct and not the code. Curiously enough, OpenSolaris > > does the same thing (it writes 0x2 followed by 0x6), but it has some sort of > > comment which implies that you have to do a write to set or clear bit 1 > > before setting bit 2. Linux only uses 0xcf9 on a specific x86 machine (View > > workstation or some such) in which case it just does a single write of 0x6. > > I'll test locally to make sure 0x4 and 0x6 both work and if so I will commit > > the fix. > > And this code is most likely never reached in majority of the cases, > reset via keyboard controller should just work. Except on boxes where it doesn't (and hence why I added it). > BTW, I understand that there is a difference between hard and soft reset > in terms of hardware signals being asserted, but I don't quite > understand general consequences. I.e. what is a practical difference > between hard and soft reset? I've no idea. It may be that we should just always do a hard reset as that is in effect what both Solaris and Linux do. I'll probably just change it to do that. -- John Baldwin
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