Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934461Ab3DHHYV (ORCPT ); Mon, 8 Apr 2013 03:24:21 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54541 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751936Ab3DHHYU (ORCPT ); Mon, 8 Apr 2013 03:24:20 -0400 Message-ID: <51626D3D.4000907@redhat.com> Date: Mon, 08 Apr 2013 15:09:49 +0800 From: Dave Young User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120605 Thunderbird/13.0 MIME-Version: 1.0 To: Yinghai Lu CC: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , WANG Chao , Vivek Goyal , "Eric W. Biederman" , linux-kernel@vger.kernel.org Subject: Re: [PATCH v3 1/4] x86, kdump: Set crashkernel_low automatically References: <1365113821-22749-1-git-send-email-yinghai@kernel.org> <1365113821-22749-2-git-send-email-yinghai@kernel.org> In-Reply-To: <1365113821-22749-2-git-send-email-yinghai@kernel.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6936 Lines: 193 On 04/05/2013 06:16 AM, Yinghai Lu wrote: > Chao said that kdump does does work well on his system on 3.8 > without extra parameter, even iommu does not work with kdump. > And now have to append crashkernel_low=Y in first kernel to make > kdump work. > > We have now modified crashkernel=X to allocate memory beyong 4G (if > available) and do not allocate low range for crashkernel if the user > does not specify that with crashkernel_low=Y. This causes regression > if iommu is not enabled. Without iommu, swiotlb needs to be setup in > first 4G and there is no low memory available to second kernel. Is it possible to reuse the 1st kernel swiotlb region in 2nd capture kernel if it's available? > > Set crashkernel_low automatically if the user does not specify that. > > For system that does support IOMMU with kdump properly, user could > specify crashkernel_low=0 to save that 72M low ram. How about make swiotlb size tunable in 1st kernel as well such as adding a swiotlb_size= to cmdline, if it's set in 1st kernel crashkernel reserving code can take it automaticlly. This will benefit to user who use low-mem machines. > > -v3: add swiotlb_size() according to Konrad. > -v4: add comments what 8M is for according to hpa. > also update more crashkernel_low= in kernel-parameters.txt > -v5: update changelog according to Vivek. > -v6: Change description about swiotlb referring according to HATAYAMA. > > Reported-by: WANG Chao > Tested-by: WANG Chao > Signed-off-by: Yinghai Lu > > --- > Documentation/kernel-parameters.txt | 14 +++++++++++--- > arch/x86/kernel/setup.c | 20 +++++++++++++++++--- > include/linux/swiotlb.h | 1 + > lib/swiotlb.c | 19 +++++++++++++++---- > 4 files changed, 44 insertions(+), 10 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 > @@ -519,19 +519,33 @@ static void __init reserve_crashkernel_l > unsigned long long low_base = 0, low_size = 0; > unsigned long total_low_mem; > unsigned long long base; > + bool auto_set = false; > int ret; > > total_low_mem = memblock_mem_size(1UL<<(32-PAGE_SHIFT)); > ret = parse_crashkernel_low(boot_command_line, total_low_mem, > &low_size, &base); > - if (ret != 0 || low_size <= 0) > - return; > + if (ret != 0) { > + /* > + * two parts from lib/swiotlb.c: > + * swiotlb size: user specified with swiotlb= or default. > + * swiotlb overflow buffer: now is hardcoded to 32k, > + * round to 8M to cover more others. > + */ > + low_size = swiotlb_size_or_default() + (8UL<<20); > + auto_set = true; > + } else { > + /* passed with crashkernel_low=0 ? */ > + if (!low_size) > + return; > + } > > low_base = memblock_find_in_range(low_size, (1ULL<<32), > low_size, alignment); > > if (!low_base) { > - pr_info("crashkernel low reservation failed - No suitable area found.\n"); > + if (!auto_set) > + pr_info("crashkernel low reservation failed - No suitable area found.\n"); > > return; > } > Index: linux-2.6/include/linux/swiotlb.h > =================================================================== > --- linux-2.6.orig/include/linux/swiotlb.h > +++ linux-2.6/include/linux/swiotlb.h > @@ -25,6 +25,7 @@ extern int swiotlb_force; > extern void swiotlb_init(int verbose); > int swiotlb_init_with_tbl(char *tlb, unsigned long nslabs, int verbose); > extern unsigned long swiotlb_nr_tbl(void); > +unsigned long swiotlb_size_or_default(void); > extern int swiotlb_late_init_with_tbl(char *tlb, unsigned long nslabs); > > /* > Index: linux-2.6/lib/swiotlb.c > =================================================================== > --- linux-2.6.orig/lib/swiotlb.c > +++ linux-2.6/lib/swiotlb.c > @@ -105,9 +105,9 @@ setup_io_tlb_npages(char *str) > if (!strcmp(str, "force")) > swiotlb_force = 1; > > - return 1; > + return 0; > } > -__setup("swiotlb=", setup_io_tlb_npages); > +early_param("swiotlb", setup_io_tlb_npages); > /* make io_tlb_overflow tunable too? */ > > unsigned long swiotlb_nr_tbl(void) > @@ -115,6 +115,18 @@ unsigned long swiotlb_nr_tbl(void) > return io_tlb_nslabs; > } > EXPORT_SYMBOL_GPL(swiotlb_nr_tbl); > + > +/* default to 64MB */ > +#define IO_TLB_DEFAULT_SIZE (64UL<<20) > +unsigned long swiotlb_size_or_default(void) > +{ > + unsigned long size; > + > + size = io_tlb_nslabs << IO_TLB_SHIFT; > + > + return size ? size : (IO_TLB_DEFAULT_SIZE); > +} > + > /* Note that this doesn't work with highmem page */ > static dma_addr_t swiotlb_virt_to_bus(struct device *hwdev, > volatile void *address) > @@ -188,8 +200,7 @@ int __init swiotlb_init_with_tbl(char *t > void __init > swiotlb_init(int verbose) > { > - /* default to 64MB */ > - size_t default_size = 64UL<<20; > + size_t default_size = IO_TLB_DEFAULT_SIZE; > unsigned char *vstart; > unsigned long bytes; > > Index: linux-2.6/Documentation/kernel-parameters.txt > =================================================================== > --- linux-2.6.orig/Documentation/kernel-parameters.txt > +++ linux-2.6/Documentation/kernel-parameters.txt > @@ -596,9 +596,6 @@ bytes respectively. Such letter suffixes > is selected automatically. Check > Documentation/kdump/kdump.txt for further details. > > - crashkernel_low=size[KMG] > - [KNL, x86] parts under 4G. > - > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > in the running system. The syntax of range is > @@ -606,6 +603,17 @@ bytes respectively. Such letter suffixes > a memory unit (amount[KMG]). See also > Documentation/kdump/kdump.txt for an example. > > + crashkernel_low=size[KMG] > + [KNL, x86_64] range under 4G. When crashkernel= is > + passed, kernel allocate physical memory region > + above 4G, that cause second kernel crash on system > + that require some amount of low memory, e.g. swiotlb > + requires at least 64M+32K low memory. Kernel would > + try to allocate 72M below 4G automatically. > + This one let user to specify own low range under 4G > + for second kernel instead. > + 0: to disable low allocation. > + > cs89x0_dma= [HW,NET] > Format: > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- Thanks Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/