Date: Wed, 4 Oct 2006 13:41:33 -0400 From: John Baldwin <jhb@freebsd.org> To: Andrea Bittau <a.bittau@cs.ucl.ac.uk> Cc: freebsd-acpi@freebsd.org, freebsd-mobile@freebsd.org Subject: Re: hack for getting suspend/resume to half work on an IBM Thinkpad x60s [SMP] Message-ID: <200610041341.34231.jhb@freebsd.org> In-Reply-To: <20061003213356.GA6149@shorty.sorbonet.org> References: <20060921000628.GA1832@shorty.sorbonet.org> <4522D023.9090501@root.org> <20061003213356.GA6149@shorty.sorbonet.org>
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On Tuesday 03 October 2006 17:33, Andrea Bittau wrote: > On Tue, Oct 03, 2006 at 02:03:31PM -0700, Nate Lawson wrote: > > I agree. The standard switch to protected mode, paging, etc. needs to > > be performed and then resume from the saved register context. > > I guess my point was that there are two pieces of code that do that: > 1) mpboot.s bootMP() used by system bootstrap and what my current patch uses. I > think this is what you guys are suggesting to use, and I'm doing it anyway in > my patch, but I just want to be the devil's advocate =D. > > 2) acpi_wakecode.S wakeup_16() used by the BSP to wake itself up. This is what > I was suggesting should be generalized and used by the other cores too. The > difference of this code as opposed to #1 is that #2 can "cheat". That is, we > can create the code for #2 on the fly and do stuff like mov old_eax,eax etc > and don't have to be smart about figuring out where the CPU should land and > how it should initialize itself [as in the case of #1]. > > I'm just wondering whether we should do something about the assembly "code > duplication" in #1 and #2. I understand they serve a different purpose, but > arguably, they do the same thing: real-mode -> jump in kernel. What is > different is what happens once in kernel mode: boot or resume? That difference > could be coded in the C part of the kernel leaving a single asm entry point both > for bootstrap and wakeup code. Am I making any sense? =D 1) is already tailored to work with starting up an extra AP based on the STARTUP IPI, so I think we should reuse it for starting up the cores. I need to think about it more though. First we need to get APIC with UP working though. -- John Baldwin
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