-----Original Message----- > ----- Original Message ----- > > Hi Kazu, > > > > On 02/20/2019 02:17 AM, Kazuhito Hagio wrote: > > > Hi Bhupesh, > > > > > > -----Original Message----- > > >> I am not sure you got a chance to look at the two regression cases I > > >> reported here: > > >> <http://lists.infradead.org/pipermail/kexec/2019-February/022449.html> > > >> > > >> Unfortunately the above suggestion doesn't provide any fix for > > >> ARMv8.2-LPA regression (see text under heading ' > > >> (1). Regression Case 1 (ARMv8.2-LPA enabled kernel)') > > > > > > As for MAX_PHYSMEM_BITS, I realized that ppc64 makedumpfile can detect > > > it because there is only one SECTION_SIZE_BITS for ppc64. I think we > > > can use the same way as set_ppc64_max_physmem_bits() does also for > > > arm64 for now. I'm going to write it for kernels not having > > > NUMBER(MAX_PHYSMEM_BITS) in vmcoreinfo. > > > > I see two drawbacks with the above approach: > > > > a). This means that other user-space tools like crash-utility would > > still be broken and would probably need to find MAX_PHYSMEM_BITS for > > arm64 via a similar (hack'ish ?) approach. > > > > b). I am looking at the makedumpfile code for 'MAX_PHYSMEM_BITS' > > determination for two archs as an example: > > > > ppc > > --- > > > > int > > set_ppc64_max_physmem_bits(void) > > { > > long array_len = ARRAY_LENGTH(mem_section); > > /* > > * The older ppc64 kernels uses _MAX_PHYSMEM_BITS as 42 and the > > * newer kernels 3.7 onwards uses 46 bits. > > */ > > > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_ORIG ; > > if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) > > || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) > > return TRUE; > > > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_3_7; > > if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) > > || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) > > return TRUE; > > > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_4_19; > > if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) > > || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) > > return TRUE; > > > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_4_20; > > if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME())) > > || (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT()))) > > return TRUE; > > > > return FALSE; > > } > > > > x86_64: > > ------ > > > > int > > get_versiondep_info_x86_64(void) > > { > > /* > > * On linux-2.6.26, MAX_PHYSMEM_BITS is changed to 44 from 40. > > */ > > if (info->kernel_version < KERNEL_VERSION(2, 6, 26)) > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_ORIG; > > else if (info->kernel_version < KERNEL_VERSION(2, 6, 31)) > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_2_6_26; > > else if(check_5level_paging()) > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_5LEVEL; > > else > > info->max_physmem_bits = _MAX_PHYSMEM_BITS_2_6_31; > > > > ... > > } > > > > Looking at the above, two questions come to my mind: > > > > - Do we really need all the above complexity in user-space code, to hoop > > across various kernel versions and perform allocations for something > > that can be so easily exported via vmcoreinfo? Also we need to see how > > portable is the above code for a new kernel version - IMO, it will need > > another fix patch when we update to a new kernel version in near future. > > I agree -- not to mention that the "kernel version" way of determining things > does not account for distribution-specific backports. > > > > > - Also do we need to replicate the above implementations across > > user-space tools when they can also utilize the vmcoreinfo information > > to determine the PA_BITS range without any additional arch/kernel > > version specific details as the single point of obtaining this > > information from the kernel? > > > > So, in view of the above, I would still advocate that we use a > > vmcoreinfo export for 'MAX_PHYSMEM_BITS' as well to have a uniform > > interface for the same across all user-land applications. > > Again, totally agree. I also agree that we should do so. Then it will be better to have it in kernel core code, not in arch-specific code. Although makedumpfile may have to have the kludge for kernels that support 52-bit PA and don't have the exported MAX_PHYSMEM_BITS sooner or later.. Thanks, Kazu > > Dave > > > > Thanks, > > Bhupesh > > > > > > _______________________________________________ > kexec mailing list > kexec@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/kexec _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
