Hi, Note that my answer does not take into account the handling of high memory in the Linux 2.4.x kernel (which I don't understand yet). It is based on my undestanding of the Linux 2.2.x kernel As far as I know, there are no VM areas for kernel memory. Kernel pointers fall into two classes: 1) They may be within the start region of kernel virtual addresses (the addresses between PAGE_OFFSET and PAGE_OFFSET + size of physical memory). This region provides a 1:1 mapping between physikal and (kernel) virtual addresses, phys_to_virt() and virt_to_phys() provide conversion between (kernel) virtual addresses from this region and physikal addresses. As far as I know, there is no higher level structure (such as vm_area structures) describing areas within this region of virtual addresses. virtual addresses within this region are returned e.g. by kmalloc() or __get_free_pages(). 2) They may be from the region above PAGE_OFFSET + size of physical memory. Addresses in this region are mapped through page tables onto physical memory (if they are mapped - they don't need to be). Pointers of this class are returned by vmalloc(). Areas within this second region are described by a descriptor of type struct vm_struct (which contains flags, start address, size and a pointer to the next descriptor). Those descriptors are linked into a list called vmlist. However, as far as I know, this list is not exported by the kernel, i.e. you can't access it from a module (but I don't think you should need access to it either). regards Martin Fabrice Tchakountio wrote: > Hi all - > > My name is Fabrice. I'm currently working on Linux 2.4.2 kernel which is > part of Red-Hat 7.1 package. I'm hacking on the VM system of Linux. > My question is: > Given a kernel pointer ( pointer to a given kernel data structure), how > can we find the appropriate VM area instance? > > for a userland pointer , we can do: > > u_vma=find_vma(current->mm, u_ptr) > > Thanks > Fabrice > > - > Kernelnewbies: Help each other learn about the Linux kernel. > Archive: http://mail.nl.linux.org/kernelnewbies/ > IRC Channel: irc.openprojects.net / #kernelnewbies > Web Page: http://www.kernelnewbies.org/ -- Supercomputing System AG email: maletinsky@scs.ch Martin Maletinsky phone: +41 (0)1 445 16 05 Technoparkstrasse 1 fax: +41 (0)1 445 16 10 CH-8005 Zurich - Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ IRC Channel: irc.openprojects.net / #kernelnewbies Web Page: http://www.kernelnewbies.org/
