Messages in this thread | | | Date | Tue, 1 Apr 2008 12:00:36 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] Configure out DMI scanning code v2 (Linux Tiny) |
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Question for Ingo...
On Tue, 12 Feb 2008 10:04:18 +0100 Thomas Petazzoni <thomas.petazzoni@free-electrons.com> wrote:
> Hi, > > Enclosed patch is an updated version, with proper credits to Matt > Mackall and the Linux Tiny project. > > Sincerly, > > Thomas > > --- > > Turn CONFIG_DMI into a selectable option if EMBEDDED is defined, in > order to be able to remove the DMI table scanning code if it's not > needed, and then reduce the kernel code size. > > With CONFIG_DMI (i.e before) : > > text data bss dec hex filename > 1076076 128656 98304 1303036 13e1fc vmlinux > > Without CONFIG_DMI (i.e after) : > > text data bss dec hex filename > 1068092 126308 98304 1292704 13b9a0 vmlinux > > Result: > > text data bss dec hex filename > -7984 -2348 0 -10332 -285c vmlinux > > The new option appears in "Processor type and features", only when > CONFIG_EMBEDDED is defined. > > This patch is part of the Linux Tiny project, and is based on previous > work done by Matt Mackall <mpm@selenic.com>. > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> > > --- > arch/x86/Kconfig | 12 +++++++++--- > include/linux/dmi.h | 1 + > 2 files changed, 10 insertions(+), 3 deletions(-) > > Index: linux/arch/x86/Kconfig > =================================================================== > --- linux.orig/arch/x86/Kconfig 2008-02-11 16:51:50.000000000 +0100 > +++ linux/arch/x86/Kconfig 2008-02-11 17:48:15.000000000 +0100 > @@ -88,9 +88,6 @@ > config ARCH_MAY_HAVE_PC_FDC > def_bool y > > -config DMI > - def_bool y > - > config RWSEM_GENERIC_SPINLOCK > def_bool !X86_XADD > > @@ -433,6 +430,15 @@ > > # Mark as embedded because too many people got it wrong. > # The code disables itself when not needed. > +config DMI > + default y > + bool "Enable DMI scanning" if EMBEDDED > + help > + Enabled scanning of DMI to identify machine quirks. Say Y > + here unless you have verified that your setup is not > + affected by entries in the DMI blacklist. Required by PNP > + BIOS code. > +
This introduces a build error in drivers/acpi/thermal.c, because that code does:
#ifdef CONFIF_DMI <define some tables> #endif
... dmi_check_system(<those tables>);
Now, the approved fix here is to just remove the ifdefs. The !CONFIG_DMI version of dmi_check_system() won't generate any references to the tables and the build system is then supposed to remove the generated code and data from vmlinux.
But this doesn't work.
When I add an ifdef around the dmi_check_system() call, I get
text data bss dec hex filename 1614279 210524 159992 1984795 1e491b vmlinux
but when I remove the ifdefs around the tables and rely on the compiler removing the code and data I get
text data bss dec hex filename 1614447 210972 159992 1985411 1e4b83 vmlinux
An additional 616 bytes of useless stuff.
Ingo, I think there was some trick to making this work right. Do you recall?
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