Hi, Let’s assume WARNING message says something like: [ 0.000000] Call Trace: [ 0.000000] [<ffffffff81762590>] dump_stack+0x45/0x56 [ 0.000000] [<ffffffff8106dd2d>] warn_slowpath_common+0x7d/0xa0 [ 0.000000] [<ffffffff8106dde4>] warn_slowpath_fmt_taint+0x44/0x50 [ 0.000000] [<ffffffff8143329c>] ? acpi_tb_acquire_table+0x3e/0x6c [ 0.000000] [<ffffffff81765070>] warn_invalid_dmar+0x81/0x93 [ 0.000000] [<ffffffff81d8989d>] detect_intel_iommu+0xe9/0x172 [ 0.000000] [<ffffffff81d3c84f>] pci_iommu_alloc+0x4a/0x6c [ 0.000000] [<ffffffff81d4cb4b>] mem_init+0x17/0x9c [ 0.000000] [<ffffffff81d31e80>] start_kernel+0x23b/0x47d [ 0.000000] [<ffffffff81d31a4e>] ? set_init_arg+0x53/0x53 [ 0.000000] [<ffffffff81d31120>] ? early_idt_handlers+0x120/0x120 [ 0.000000] [<ffffffff81d315ee>] x86_64_start_reservations+0x2a/0x2c [ 0.000000] [<ffffffff81d31733>] x86_64_start_kernel+0x143/0x152 [ 0.000000] ---[ end trace c32c0e307381ad8a ]--- Few symbols in the above mentioned call trace are prefixed with “?” (for e.g. ?early_idt_handlers\? set_init_arg\? acpi_tb_acquire_table), what does it mean? Does it needs to be considered while debugging the kernel module? Call Trace shows “function+0xoffset/0xlength”. Does the 0xoffset/0xlength changes if the module is built with –g option and without –g option? Thanks in Advance, -- Thanks, Sekhar