Memory-Hotplug: Fix the bug on interface /dev/mem for 64-bit kernel(v1)
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From: Zheng, Shaohui on 12 Jan 2010 01:00 > > + /* if add to low memory, update max_low_pfn */ > > + if (unlikely(start_pfn < limit_low_pfn)) { > > + if (end_pfn <= limit_low_pfn) > > + max_low_pfn = end_pfn; > > + else > > + max_low_pfn = limit_low_pfn; > > X86_64 actually always set max_low_pfn=max_pfn, in setup_arch(): > [Zheng, Shaohui] there should be some misunderstanding, I read the > code carefully, if the total memory is under 4G, it always > max_low_pfn=max_pfn. If the total memory is larger than 4G, > max_low_pfn means the end of low ram. It set > max_low_pfn = e820_end_of_low_ram_pfn();. The above line is very misleading.. In setup_arch(), it will be overrode by the following block. [Zheng, Shaohui] yes, I misunderstand it because of this code. It seems that max_low_pfn == max_pfn is always true on x86_32 and x86_64. Thanks fengguang to point it out. > 899 #ifdef CONFIG_X86_64 > 900 if (max_pfn > max_low_pfn) { > 901 max_pfn_mapped = init_memory_mapping(1UL<<32, > 902 max_pfn<<PAGE_SHIFT); > 903 /* can we preseve max_low_pfn ?*/ > 904 max_low_pfn = max_pfn; > 905 } > 906 #endif Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Wu Fengguang on 12 Jan 2010 08:40 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(a)intel.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(a)firstfloor.org> > > CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > > Signed-off-by: Wu Fengguang <fengguang.wu(a)intel.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(). Thanks, Fengguang -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Wu Fengguang on 12 Jan 2010 21:40
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(a)intel.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(a)intel.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(a)firstfloor.org> > >> > CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com> > >> > Signed-off-by: Wu Fengguang <fengguang.wu(a)intel.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(a)kernel.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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |