On Mon, Nov 11, 2013 at 12:57:12PM -0800, H. Peter Anvin wrote: > It is pretty simple: the kernel exports how much text+data+bss+brk it needs, and the kernel cannot use memory outside that region until it is ready to control the address space itself. Ok. So looks like that field is. 0260/4 2.10+ init_size Linear memory required during initialization This helps. Thanks. Vivek > > Vivek Goyal <vgoyal at redhat.com> wrote: > >Hi, > > > >I am staring at control page allocation logic in case of kdump and > >wondering what makes sure that these pages are not overwritten by > >next kernel. > > > >I see that for 64bit entry, control pages have the page tables needed > >for second kernel. In case of crash these pages from from crash kernel > >reserved region. Page allocator is very simple and that is start from > >lowest crash reserved range and move higher and allocate first > >available > >page which is not allocated to segments. What makes sure that these > >pages > >are not overwritten by second kernel. > > > >I guess it becomes a general bootloader question. How do we make sure > >bootloader prepared page tables/gdt will not be overwritten by kernel > >(till kernel sets up its own page tables and gdt) and how should we do > >the > >allocation and placement. > > > >Thanks > >Vivek > > -- > Sent from my mobile phone. Please pardon brevity and lack of formatting.
