linux-kernel - Re: MPTable can not be high-memory on Linux

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Message-Id: <200902221806.55429.rjw@sisk.pl>
Date:	Sun, 22 Feb 2009 18:06:54 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	"Kevin O'Connor" <kevin@...onnor.net>
Cc:	Stefan Reinauer <stepan@...esystems.de>,
	linux-kernel@...r.kernel.org, coreboot@...eboot.org,
	Ingo Molnar <mingo@...e.hu>,
	Jaswinder Singh Rajput <jaswinder@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>
Subject: Re: MPTable can not be high-memory on Linux

On Sunday 22 February 2009, Kevin O'Connor wrote:
> Hi Stefan,
> 
> I'm CC'ing lkml and coreboot mailing lists.

(added more CCs)

> On Thu, Feb 19, 2009 at 10:26:17PM +0100, Stefan Reinauer wrote:
> > OK, I played some more, and I finally found out it's earlyprintk and not
> > early_printk. Plus there is bootmem_debug:
> > 
> > Initializing cgroup subsys cpuset
> > Initializing cgroup subsys cpu
> > Linux version 2.6.27.7-9-default (geeko@...ldhost) (gcc version 4.3.2
> > [gcc-4_3-branch re0
> > PAT WC disabled due to known CPU erratum.
> > BIOS-provided physical RAM map:
> >  BIOS-e820: 0000000000000000 - 0000000000001000 (reserved)
> >  BIOS-e820: 0000000000001000 - 0000000000090000 (usable)
> >  BIOS-e820: 0000000000090000 - 0000000000100000 (reserved)
> >  BIOS-e820: 0000000000100000 - 000000003f7f0000 (usable)
> >  BIOS-e820: 000000003f7f0000 - 0000000040000000 (reserved)
> >  BIOS-e820: 00000000f0000000 - 00000000f4000000 (reserved)
> [...]
> > ACPI: no DMI BIOS year, acpi=force is required to enable ACPI
> > ACPI: Disabling ACPI support
> [...]
> > found SMP MP-table at [c00f9fc0] 000f9fc0
> > bootmem::mark_bootmem_node nid=0 start=f9 end=fb reserve=1 flags=0
> > bootmem::__reserve nid=0 start=f9 end=fb flags=0
> > bootmem::__reserve silent double reserve of PFN f9
> > bootmem::__reserve silent double reserve of PFN fa
> > BUG: Int 6: CR2 00000000
> >      EDI c00f9fd0  ESI 3f7f5410  EBP 0003f7f5  ESP c0535f20
> >      EBX c056c00c  EDX 00000006  ECX 00000001  EAX c056c03c
> >      err 00000000  EIP c054f8f0   CS 00000060  flg 00010046
> > Stack: 00000000 00000000 00000001 00038000 0003f7f5 f880abf0 3f7f5410
> > c00f9fd0
> >        00000001 c054f91d 00000000 c054571a c0413e7e c00f9fc0 000f9fc0
> > 00000001
> >        3f7bf64d 00000000 3e2c5000 c054578a 00000000 c053f3b6 3f7bf64d
> > 00000000
> > 
> > So it dies because of the way it tries to reserve the MP-table.
> > 
> > Here's the stack trace.
> > 
> >  [<c054f8f0>] mark_bootmem+0x9b/0xab
> >  [<c054f91d>] reserve_bootmem+0x1d/0x1f
> >  [<c054571a>] smp_scan_config+0xd9/0xfa
> >  [<c054578a>] __find_smp_config+0x4f/0x6e
> >  [<c053f3b6>] setup_arch+0x576/0x639
> >  [<c054ebc4>] cgroup_init_subsys+0x29/0xc9
> >  [<c053a6ac>] start_kernel+0x6b/0x31f
> >  =======================
> 
> It looks like the problem is that the MPTable is located in the last
> 64K of memory (instead of the first few megabytes).  There is a
> comment about this in arch/x86/kernel/mpparse.c:
> 
>    /*
>     * We cannot access to MPC table to compute
>     * table size yet, as only few megabytes from
>     * the bottom is mapped now.
>     * PC-9800's MPC table places on the very last
>     * of physical memory; so that simply reserving
>     * PAGE_SIZE from mpg->mpf_physptr yields BUG()
>     * in reserve_bootmem.
>     */
> 
> However, that comment is in an #ifdef specific to 32bit kernels.
> (Though, it's not clear to me how that code would help as it sets size
> to be a negative number.)
> 
> The easiest way to fix this is to change SeaBIOS to copy the whole
> mptable to the first megabyte.  Also, we need to fix your SMBIOS so
> that ACPI is used instead of the mptable.
> 
> -Kevin
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