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Date: Wed, 13 Jan 2010 10:29:48 +0800
From: Wu Fengguang <fengguang.wu@...el.com>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
"Zheng, Shaohui" <shaohui.zheng@...el.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"ak@...ux.intel.com" <ak@...ux.intel.com>,
"y-goto@...fujitsu.com" <y-goto@...fujitsu.com>,
Dave Hansen <haveblue@...ibm.com>,
"x86@...nel.org" <x86@...nel.org>
Subject: Re: [PATCH - resend] Memory-Hotplug: Fix the bug on interface
/dev/mem for 64-bit kernel(v1)
On Wed, Jan 13, 2010 at 07:01:47AM +0800, Yinghai Lu wrote:
> On Tue, Jan 12, 2010 at 5:35 AM, Wu Fengguang <fengguang.wu@...el.com> wrote:
> > On Tue, Jan 12, 2010 at 10:39:03AM +0800, KAMEZAWA Hiroyuki wrote:
> >> On Tue, 12 Jan 2010 10:33:08 +0800
> >> Wu Fengguang <fengguang.wu@...el.com> wrote:
> >>
> >> > Sure, here it is :)
> >> > ---
> >> > x86: use the generic page_is_ram()
> >> >
> >> > The generic resource based page_is_ram() works better with memory
> >> > hotplug/hotremove. So switch the x86 e820map based code to it.
> >> >
> >> > CC: Andi Kleen <andi@...stfloor.org>
> >> > CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
> >> > Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>
> >>
> >> Ack.
> >
> > Thank you.
> >
> >>
> >> > +#ifdef CONFIG_X86
> >> > + /*
> >> > + * A special case is the first 4Kb of memory;
> >> > + * This is a BIOS owned area, not kernel ram, but generally
> >> > + * not listed as such in the E820 table.
> >> > + */
> >> > + if (pfn == 0)
> >> > + return 0;
> >> > +
> >> > + /*
> >> > + * Second special case: Some BIOSen report the PC BIOS
> >> > + * area (640->1Mb) as ram even though it is not.
> >> > + */
> >> > + if (pfn >= (BIOS_BEGIN >> PAGE_SHIFT) &&
> >> > + pfn < (BIOS_END >> PAGE_SHIFT))
> >> > + return 0;
> >> > +#endif
> >>
> >> I'm glad if this part is sorted out in clean way ;)
> >
> > Two possible solutions are:
> >
> > - to exclude the above two ranges directly in e820 map;
> > - to not add the above two ranges into iomem_resource.
> >
> > Yinghai, do you have any suggestions?
> > We want to get rid of the two explicit tests from page_is_ram().
>
> please check attached patch.
>
> YH
Thank you, it works!
Content-Description: remove_bios_begin_end.patch
> [PATCH] x86: remove bios data range from e820
>
> to prepare move page_is_ram as generic one
>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org.
Malformed email address..
> ---
> arch/x86/kernel/e820.c | 8 ++++++++
> arch/x86/kernel/head32.c | 2 --
> arch/x86/kernel/head64.c | 2 --
> arch/x86/kernel/setup.c | 19 ++++++++++++++++++-
> arch/x86/mm/ioremap.c | 16 ----------------
> 5 files changed, 26 insertions(+), 21 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/setup.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/setup.c
> +++ linux-2.6/arch/x86/kernel/setup.c
> @@ -657,6 +657,23 @@ static struct dmi_system_id __initdata b
> {}
> };
>
> +static void __init trim_bios_range(void)
How about e820_trim_bios_range() ?
> +{
> + /*
> + * A special case is the first 4Kb of memory;
> + * This is a BIOS owned area, not kernel ram, but generally
> + * not listed as such in the E820 table.
> + */
> + e820_update_range(0, PAGE_SIZE, E820_RAM, E820_RESERVED);
> + /*
> + * special case: Some BIOSen report the PC BIOS
> + * area (640->1Mb) as ram even though it is not.
> + * take them out.
> + */
> + e820_remove_range(BIOS_BEGIN, BIOS_END - BIOS_BEGIN, E820_RAM, 1);
> + sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
> +}
> +
> Index: linux-2.6/arch/x86/kernel/head32.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/head32.c
> +++ linux-2.6/arch/x86/kernel/head32.c
> @@ -29,8 +29,6 @@ static void __init i386_default_early_se
>
> void __init i386_start_kernel(void)
> {
> - reserve_early_overlap_ok(0, PAGE_SIZE, "BIOS data page");
> -
> #ifdef CONFIG_X86_TRAMPOLINE
> /*
> * But first pinch a few for the stack/trampoline stuff
> Index: linux-2.6/arch/x86/kernel/head64.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/head64.c
> +++ linux-2.6/arch/x86/kernel/head64.c
> @@ -98,8 +98,6 @@ void __init x86_64_start_reservations(ch
> {
> copy_bootdata(__va(real_mode_data));
>
> - reserve_early_overlap_ok(0, PAGE_SIZE, "BIOS data page");
> -
> reserve_early(__pa_symbol(&_text), __pa_symbol(&__bss_stop), "TEXT DATA BSS");
>
> #ifdef CONFIG_BLK_DEV_INITRD
The above two trunks don't apply in latest linux-next.
Not a big problem for my test though.
Thanks,
Fengguang
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