2.2.18: apm initialised before dmi_scan?

2.2.18: apm initialised before dmi_scan?

[Neale Banks]

Hi Stephen,

Looking more closely at a 2.2.18 bootup tonight I see that apm stuff
appears in dmesg before dmi_scan does (I added "#define DUMP_DMI" in
dmi_scan.c).

If this implies that apm is initialised *before* the dmi_scan then there
is potentially a problem with buggy BIOSen that oops instead of reporting
power status, given:

* passing the boot-parameter apm=debug causes a power status report as apm
is initialised

* dmi_scan is identifying at least one machine that oopses when the power
status report BIOS call is invoked.

... so with a buggy BIOS and "apm=debug" it's vital that the dmi_scan is
completed *before* apm is initialised - which is not what I am seeing with
2.2.18 (nor can I see where the order of such things is set).  The test
would be to boot a buggy Dell with "apm=debug" (and "#define DUMP_DMI" in
dmi_scan.c - but if my theory is right it won't get that far) and watch
for smoke leakage.

I think it's obvious that this would all go away if apm is a module (as it
can be with 2.4).

Regards,
Neale.

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Re: 2.2.18: apm initialised before dmi_scan?

[Keith Owens]

On Tue, 30 Jan 2001 22:47:02 +1100 (EST), 
Neale Banks <neale@lowendale.com.au> wrote:
>Looking more closely at a 2.2.18 bootup tonight I see that apm stuff
>appears in dmesg before dmi_scan does (I added "#define DUMP_DMI" in
>dmi_scan.c).
>
>If this implies that apm is initialised *before* the dmi_scan then there
>is potentially a problem with buggy BIOSen that oops instead of reporting
>power status

This should fix the link order, at the (small) expense of compiling
dmi_scan for exported symbols, even though it does not really export
symbols.  Against 2.2.18.

Index: 18.1/arch/i386/kernel/Makefile
--- 18.1/arch/i386/kernel/Makefile Thu, 23 Nov 2000 11:48:07 +1100 kaos (linux-2.2/E/b/40_Makefile 1.1.4.4 644)
+++ 18.2(w)/arch/i386/kernel/Makefile Tue, 30 Jan 2001 23:47:17 +1100 kaos (linux-2.2/E/b/40_Makefile 1.1.4.4 644)
@@ -15,8 +15,8 @@ all: kernel.o head.o init_task.o
 O_TARGET := kernel.o
 O_OBJS   := process.o signal.o entry.o traps.o irq.o vm86.o \
             ptrace.o ioport.o ldt.o setup.o time.o sys_i386.o \
-	    bluesmoke.o dmi_scan.o
-OX_OBJS  := i386_ksyms.o
+	    bluesmoke.o
+OX_OBJS  := i386_ksyms.o dmi_scan.o
 MX_OBJS  :=
 
 ifdef CONFIG_PCI

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Re: 2.2.18: apm initialised before dmi_scan?

[Neale Banks]

On Tue, 30 Jan 2001, Keith Owens wrote:

> >If this implies that apm is initialised *before* the dmi_scan then there
> >is potentially a problem with buggy BIOSen that oops instead of reporting
> >power status
> 
> This should fix the link order, at the (small) expense of compiling
> dmi_scan for exported symbols, even though it does not really export
> symbols.  Against 2.2.18.
> 
> Index: 18.1/arch/i386/kernel/Makefile
> --- 18.1/arch/i386/kernel/Makefile Thu, 23 Nov 2000 11:48:07 +1100 kaos (linux-2.2/E/b/40_Makefile 1.1.4.4 644)
> +++ 18.2(w)/arch/i386/kernel/Makefile Tue, 30 Jan 2001 23:47:17 +1100 kaos (linux-2.2/E/b/40_Makefile 1.1.4.4 644)
> @@ -15,8 +15,8 @@ all: kernel.o head.o init_task.o
>  O_TARGET := kernel.o
>  O_OBJS   := process.o signal.o entry.o traps.o irq.o vm86.o \
>              ptrace.o ioport.o ldt.o setup.o time.o sys_i386.o \
> -	    bluesmoke.o dmi_scan.o
> -OX_OBJS  := i386_ksyms.o
> +	    bluesmoke.o
> +OX_OBJS  := i386_ksyms.o dmi_scan.o
>  MX_OBJS  :=
>  
>  ifdef CONFIG_PCI

Thanks Keith - works nicely.

If this is a correct and justifiable fix for 2.2 then in 2.4 should
dmi_scan.o be included in export-objs?  Or is there a "better" way of
doing this?

Neale.

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Re: 2.2.18: apm initialised before dmi_scan?

[Keith Owens]

On Wed, 31 Jan 2001 22:54:22 +1100 (EST), 
Neale Banks <neale@lowendale.com.au> wrote:
>If this is a correct and justifiable fix for 2.2 then in 2.4 should
>dmi_scan.o be included in export-objs?  Or is there a "better" way of
>doing this?

It should already be correct in 2.4.  In 2.2 the OX_OBJS list is
independent from the O_OBJS list and OX_OBJS is linked first, causing
strange out of order problems.  In 2.4 export-objs is a subset of the
object list and export-objs does not impose any link ordering.

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