linux-kernel - Re: [3.9-rc1] Bug in bootup code or debug code?

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Date:	Thu, 14 Mar 2013 05:45:55 +0900
From:	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:	hpa@...ux.intel.com
Cc:	fenghua.yu@...el.com, dave@...ux.vnet.ibm.com,
	linux-kernel@...r.kernel.org
Subject: Re: [3.9-rc1] Bug in bootup code or debug code?

H. Peter Anvin wrote:
> On 03/13/2013 08:22 AM, Yu, Fenghua wrote:
> >>
> >> I found the location of "hardware reset" trigger.
> >>
> >> It is __pa_symbol(&boot_params) call, for I don't encounter "hardware
> >> reset" if
> >> I remove the "//" from below debug patch.
> >>
> >> This bug is not yet fixed as of 3.9.0-rc2-00188-g6c23cbb .
> >>
> >> --- a/arch/x86/kernel/microcode_intel_early.c
> >> +++ b/arch/x86/kernel/microcode_intel_early.c
> >> @@ -741,7 +741,9 @@ load_ucode_intel_bsp(void)
> >>  #ifdef CONFIG_X86_32
> >>         struct boot_params *boot_params_p;
> >>
> >> +       //while (1);
> >>         boot_params_p = (struct boot_params *)__pa_symbol(&boot_params);
> >> +       while (1);
> >>         ramdisk_image = boot_params_p->hdr.ramdisk_image;
> >>         ramdisk_size  = boot_params_p->hdr.ramdisk_size;
> >>         initrd_start_early = ramdisk_image;
> > 
> > Tetsuo and Dave,
> > 
> > That's the place where we suspected to cause the problem.
> > 
> > My question is: how to access global variable in linear mode in virtualization? __pa_symbol() is not a problem for native.
> > 
> 
> What kind of virtualization are we talking about here?  We should not be
> running this code under any paravirtualized code path -- this is the
> hypervisor's job to take care of this.  For HVM, this should just work
> the same way.
> 
> 	-hpa
> 
H. Peter Anvin wrote:
> This is a CONFIG_DEBUG_VIRTUAL configuration, isn't it?

Yes. CONFIG_MICROCODE_INTEL_EARLY=y && CONFIG_64BIT=n && CONFIG_DEBUG_VIRTUAL=y
on VMware Workstation/Player environment.
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