On 05/22/19 at 11:11am, Dave Young wrote: > Hi Baoquan, > > A few nitpicks, otherwise > Acked-by: Dave Young <dyo...@redhat.com> > > On 05/09/19 at 09:36am, Baoquan He wrote: > > Restrict kdump to only reserve crashkernel below 64TB. > > > > The reaons is that the kdump may jump from 5-level to 4-level, and if > > the kdump kernel is put above 64TB, then the jumping will fail. While the > > 1st kernel reserves crashkernel region during bootup, we don't know yet > > which kind of kernel will be loaded after system bootup, 5-level kernel > > or 5-level kernel. > > 5-level kernel or 4-level kernel ?
Right, it's typo. Should be '5-level kernel or 4-level kernel'. Thanks. Will update. > > > > Signed-off-by: Baoquan He <b...@redhat.com> > > Acked-by: Kirill A. Shutemov <kirill.shute...@linux.intel.com> > > --- > > arch/x86/kernel/setup.c | 17 ++++++++++++++--- > > 1 file changed, 14 insertions(+), 3 deletions(-) > > > > diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c > > index 905dae880563..efb0934a46f6 100644 > > --- a/arch/x86/kernel/setup.c > > +++ b/arch/x86/kernel/setup.c > > @@ -452,15 +452,26 @@ static void __init > > memblock_x86_reserve_range_setup_data(void) > > #define CRASH_ALIGN SZ_16M > > > > /* > > - * 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. > > > + * 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 > > > #endif > > > > static int __init reserve_crashkernel_low(void) > > -- > > 2.17.2 > > > > Thanks > Dave
