----- Original Message ----- > Hi, > > Latest linux kernel enabled kaslr to randomiz phys/virt memory > addresses, we had some effort to support kexec/kdump so that crash > utility can still works in case crashed kernel has kaslr enabled. > > But according to Dave Anderson virsh dump does not work, quoted messages > from Dave below: > > """ > with virsh dump, there's no way of even knowing that KASLR > has randomized the kernel __START_KERNEL_map region, because there is no > virtual address information -- e.g., like "SYMBOL(_stext)" in the kdump > vmcoreinfo data to compare against the vmlinux file symbol value. > Unless virsh dump can export some basic virtual memory data, which > they say it can't, I don't see how KASLR can ever be supported. > """
We also need the x86_64 phys_base value. As it is right now, virsh dump vmcores work by luck. It is presumed that the __START_KERNEL_map region is unmodified (i.e., what's in the vmlinux file), and the phys_base value is guessed by checking phys_base values from -16MB to +16MB in 1MB chunks. If the phys_base value is not one of those 32 possible values, the crash session will fail. Dave > > I assume virsh dump is using qemu guest memory dump facility so it > should be first addressed in qemu. Thus post this query to qemu devel > list. If this is not correct please let me know. > > Could you qemu dump people make it work? Or we can not support virt dump > as long as KASLR being enabled. Latest Fedora kernel has enabled it in > x86_64. > > Thanks > Dave >
