Andi Kleen wrote: > > > Using the latest F7 kernel and crash I'm getting the following > > > error: > > > WARNING: cannot read linux_banner string > > > crash: /usr/lib/debug/lib/modules/2.6.22.1-20.fc7/vmlinux and > > > /dev/crash do not match! > > > I've tried both crash and crash -f with no luck. > > > I've search the mailing list and was unable to find any > > > thing talked about this problem... So I'm thinking this > > > may not be a known problem... If it is, please let me know > > > otherwise does anybody have idea what the problem could be? > > > tia, > > > steved. > > > > > > > This elephant still remains in the room... > > > > I can reproduce it with a 2.6.21-1.3194.fc7 kernel, which > > I believe has 2.6.22 stuff backported to it. > > Don't know about the Fedora kernel, but at least in mainline > __pa/__va still work as before for i386/x86-64. It's a single > add/sub on i386 and on x86-64 similar, but with different ranges > for kernel text vs the other kernel memory. > > The load address is variable now, but still has a default > set at compile time in CONFIG. > > What might have changed when you enable the relocatable kernel > is that the ELF addresses in the vmlinux are different. But > at runtime there is no difference. > > -Andi Vivek Goyal wrote: > Hi Dave, > > Sorry, could not reply on Friday. > > This looks weared. Only one possible theory comes to mind. In FC7 kernels > following should be config variables. > > CONFIG_PHYSICAL_START=16MB > CONFIG_PHYSICAL_ALIGN=4MB. > > That means kernel has been compiled for 16MB physical address. That's > why linux_banner symbol address is in higher range. But at run time it > has been loaded by grub at 1MB location. Because alignment required is > 4MB kernel will move itself to physical address 4MB and that would > probably put linux banner somewhere at 6MB location. > > So these kind of problems will occur with first kernel is not run at > the address it has been compiled for. Can you please confirm this by > looking at FC7 config file. > > An easy way to fix this would be to change CONFIG_PHYSICAL_START=1MB. > > Thanks > Vivek Thanks Vivek, that restores sanity. Upon rebuilding my FC7 kernel with CONFIG_PHYSICAL_START changed from 16MB to 1MB, with CONFIG_PHYSICAL_ALIGN left at 4MB, i.e.: CONFIG_PHYSICAL_START=0x100000 CONFIG_PHYSICAL_ALIGN=0x400000 The kernel gets compiled for a 4MB physical address: $ nm -Bn vmlinux | grep "^c04" c0400000 T _text c0400000 T startup_32 c0401000 T startup_32_smp c0401080 t checkCPUtype c0401101 t is486 c0401108 t is386 c0401175 t check_x87 c04011a0 T setup_pda c04011c2 t setup_idt c04011df t rp_sidt c0401262 t early_divide_err c0401268 t early_illegal_opcode c0401271 t early_protection_fault c0401278 t early_page_fault c040127f t early_fault c04012a7 t hlt_loop c04012ac t ignore_int c04012f0 T _stext c04012f0 t run_init_process c04012f0 T stext ... and so the same virtual-to-physical translation can be used for both non-kernel unity-mapped kernel virtual addresses as well as for kernel symbol addresses. Thanks again, Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility
