Messages in this thread | | | Date | Thu, 23 May 2019 11:15:41 +0800 | From | Baoquan He <> | Subject | Re: [PATCH v4 3/3] x86/kdump/64: Change the upper limit of crashkernel reservation |
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On 05/22/19 at 11:11am, Dave Young wrote: > > /* > > - * Keep the crash kernel below this limit. On 32 bits earlier kernels > > - * would limit the kernel to the low 512 MiB due to mapping restrictions. > > + * Keep the crash kernel below this limit. > > + * > > + * On 32 bits earlier kernels would limit the kernel to the low > > + * 512 MiB due to mapping restrictions. > > + * > > + * On 64bit, old kexec-tools need to be under 896MiB. The later > > + * supports to put kernel above 4G, up to system RAM top. Here > > Above two lines are not reflected in code because we have removed > the 896M limitation, it would be better to drop the two lines to > avoid confusion.
Missed these comments at bottom of mail.
Yes, will remove these two lines.
> > > + * kdump kernel need be restricted to be under 64TB, which is > > + * the upper limit of system RAM in 4-level paing mode. Since > > + * the kdump jumping could be from 5-level to 4-level, the jumping > > + * will fail if kernel is put above 64TB, and there's no way to > > + * detect the paging mode of the kernel which will be loaded for > > + * dumping during the 1st kernel bootup. > > */ > > #ifdef CONFIG_X86_32 > > # define CRASH_ADDR_LOW_MAX SZ_512M > > # define CRASH_ADDR_HIGH_MAX SZ_512M > > #else > > # define CRASH_ADDR_LOW_MAX SZ_4G > > -# define CRASH_ADDR_HIGH_MAX MAXMEM > > +# define CRASH_ADDR_HIGH_MAX (64UL << 40) > > Maybe add a new macro in sizes.h like SZ_64T
I am fine, will add and use it here. Thanks.
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