Hi Tang, On Fri, 2013-02-01 at 09:57 +0800, Tang Chen wrote: > On 02/01/2013 09:36 AM, Simon Jeons wrote: > > On Fri, 2013-02-01 at 09:32 +0800, Jianguo Wu wrote: > >>> > >>> So if config NUMA, kernel memory will not be linear mapping anymore? For > >>> example, > >>> > >>> Node 0 Node 1 > >>> > >>> 0 ~ 10G 11G~14G > > It has nothing to do with linear mapping, I think. > > >>> > >>> kernel memory only at Node 0? Can part of kernel memory also at Node 1? > > Please refer to find_zone_movable_pfns_for_nodes(). I see, thanks. :) > The kernel is not only on node0. It uses all the online nodes evenly. :) > > >>> > >>> How big is kernel direct mapping memory in x86_64? Is there max limit? > >> > >> > >> Max kernel direct mapping memory in x86_64 is 64TB. > > > > For example, I have 8G memory, all of them will be direct mapping for > > kernel? then userspace memory allocated from where? > > I think you misunderstood what Wu tried to say. :) > > The kernel mapped that large space, it doesn't mean it is using that > large space. > The mapping is to make kernel be able to access all the memory, not for > the kernel > to use only. User space can also use the memory, but each process has > its own mapping. > > For example: > > 64TB, what ever > xxxTB, what ever > logic address space: |_____kernel_______|_________user_________________| > \ \ / / > \ /\ / > physical address space: |___\/__\/_____________| 4GB or > 8GB, what ever > ***** How much address space user process can have on x86_64? Also 8GB? > > The ***** part physical is mapped to user space in the process' own > pagetable. > It is also direct mapped in kernel's pagetable. So the kernel can also > access it. :) But how to protect user process not modify kernel memory? > > > > >> > >>> It seems that only around 896MB on x86_32. > >>> > >>>> > >>>> We need firmware take part in, such as SRAT in ACPI BIOS, or the firmware > >>>> based memory migration mentioned by Liu Jiang. > >>> > >>> Is there any material about firmware based memory migration? > > No, I don't have any because this is a functionality of machine from HUAWEI. > I think you can ask Liu Jiang or Wu Jianguo to share some with you. :) > > Thanks. :) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
