在 2018年11月15日 13:58, Dave Young 写道: > On 11/15/18 at 01:44pm, lijiang wrote: >> 在 2018年11月14日 19:26, Borislav Petkov 写道: >>> On Wed, Nov 14, 2018 at 03:29:25PM +0800, Lianbo Jiang wrote: >>>> When load the kernel image and initramfs by kexec_file_load syscall, it can >>>> not add exact e820 reserved type to kdump kernel e820 table. >>>> >>>> Kdump uses walk_iomem_res_desc() to iterate io resources, then adds matched >>>> desc to e820 table for kdump kernel. But, when convert the e820 type into >>>> the iores descriptors, several e820 types are converted to 'IORES_DES_NONE' >>>> in this function e820_type_to_iores_desc(). So the walk_iomem_res_desc() >>>> will get these unnecessary types(E820_TYPE_RAM/E820_TYPE_UNUSABLE/E820_TYPE >>>> _KERN) when iterate io resources by the 'IORES_DES_NONE'. >>>> >>>> It needs filter out these redundant type(such as E820_TYPE_RAM/E820_TYPE_ >>>> UNUSABLE/E820_TYPE_KERN) in order to add exact e820 reserved type to kdump >>>> kernel e820 table. Thus it also needs an extra checking in memmap_entry_ >>>> callback() to match the e820 type and resource name. >>> >>> Ok, it took me a while to parse what this is trying to say so let's >>> start from the top: >>> >>> * What resource type do you do need in the second kernel? >>> >> >> Thanks for your comment. >> >> The e820 reserved ranges need to be passed to the second kernel. >> >>> * The most important question: why? >>> >> >> At present, the upstream kernel does not pass the e820 reserved ranges to the >> second kernel, which might cause two problems: >> >> The first one is the MMCONFIG issue, the PCI MMCONFIG(extended mode) requires >> the reserved region otherwise it falls back to legacy mode, which might lead to >> the hot-plug device could not be recognized in kdump kernel. >> >> Another one is that the e820 reserved ranges do not setup in kdump kernel, which >> could cause kdump can't work in some machines. To know more information, please >> refer to the [PATCH 2/2 v6] patch log. >> >> >>> * If it is the reserved resource, why aren't you adding >>> IORES_DESC_RESERVED or so which to look for instead of this hacky string >>> comparison? >>> >> >> Adding the new descriptor 'IORES_DESC_RESERVED' is also a good solution. I will > > I was not sure if something else depends on IORES_DESC_NONE and if it is > easy to split it and add IORES_DESC_RESERVED > > But if you can prove it is safe then it would be a better way. > Thank you, Dave. These two solutions should be feasible, they can work very well on my machine. Regards, Lianbo > Thanks > Dave > _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
