| From: Dave Anderson <anderson@xxxxxxxxxx> | Ken'ichi Ohmichi wrote: | > On linux-2.6.22, the external declaration of i386's __per_cpu_offset[] | > is in include/asm-i386/percpu.h, and the definition of __per_cpu_offset[] | > is in init/main.c: | > | > unsigned long __per_cpu_offset[NR_CPUS] __read_mostly; | > | > | > There are their debugging information in the dwarf section, and the | > definition's one includes the array length. | > I explain by following output of the dwarfdump command. | > | > * The debugging information of "extern unsigned long __per_cpu_offset[];" | > There is not the attribute DW_AT_upper_bound and the crash utility cannot | > get the array number. | > <1><32685> DW_TAG_variable | > DW_AT_name __per_cpu_offset | > DW_AT_decl_file 83 include/asm/percpu.h | > DW_AT_decl_line 48 | > DW_AT_type <32674> | > DW_AT_external yes(1) | > DW_AT_declaration yes(1) | > <1><32674> DW_TAG_array_type | > DW_AT_sibling <32685> | > DW_AT_type <83> | > <2><32683> DW_TAG_subrange_type | > | > * The debugging information of "unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;" | > There is the attribute DW_AT_upper_bound and the crash utility can do it. | > <1><58437> DW_TAG_variable | > [a1][a1][a1][a1] DW_AT_name __per_cpu_offset | > DW_AT_decl_file 1 init/main.c | > DW_AT_decl_line 363 | > DW_AT_type <33> | > DW_AT_external yes(1) | > DW_AT_location DW_OP_addr 0xc03fd400 | > <1>< 33> DW_TAG_array_type | > DW_AT_sibling <49> | > DW_AT_type <56> | > <2>< 42> DW_TAG_subrange_type | > DW_AT_type <49> | > DW_AT_upper_bound 31 <--- Here! | > | > | > I thought get_array_length() should retry to get the array length from | > the next if it could not get it. But I prefer your following idea because | > it is simple and does not make other effects. | | I see. But as it stands now, the crash utility has no dwarfdump-like | functions to pull out such data, but rather relies on gdb to do the | dirty work. There's probably something in the gdb innards that could | access it, but I'm not aware of it. | | But it's not that important... This makes me quite suspicious. I assume that you are correct that the problem is in gdb. It still feels like there is a serious problem here: that the most complete definition is not being made available. You have an effective work-around for __per_cpu_offset, but I wonder how many other ways this same problem will come up. -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
