From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andreas Dilger Message-Id: <200009071825.MAA08578@lynx.turbolabs.com> Subject: [linux-lvm] LVM support for LILO Date: Thu, 7 Sep 2000 12:25:07 -0600 (MDT) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-lvm Errors-To: owner-linux-lvm List-Id: Content-Type: text/plain; charset="us-ascii" To: Linux LVM mailing list Cc: idsfa@visi.com Heinz, Michael Kellen and I have been working to add LILO support for booting from a LV (i.e. have /boot be an LV, and then not have ANY DOS partitions). However, the main problem that we are having is that you cannot use an LV device major/minor to do anything with liblvm. All of the liblvm functions use an LV name, it would be good to add an ioctl which takes a dev_t (e.g. 0x3a01) and returns an LV name, or maybe an lv_t which we can use with liblvm. Along the same lines, it may be good to have an ioctl which takes a dev_t and returns a vg_t of the VG which this LV is a part of. Finally, it would be good to take the code out of lvm_map() which only does block/dev remapping (which lvm_map() will call), but which also be called by an ioctl like FIBMAP. How this all fits together is: 1) LILO gets the name of a kernel image (e.g. /boot/vmlinuz) and does stat() on it to get the dev_t. 2) LILO does FIBMAP ioctl for each block in the kernel image to find the absolute block on the dev_t, and stores this into boot.map. We need to take the LV dev_t and map it to an lv_t. Then after LILO does the FIMBAP on a file block (which returns an LV relative block number), we need to call a function (ioctl) with (lv_t, lv_block) to return the PV (dev_t, block), which will then be stored in the boot.map. LILO needs the underlying dev_t, because this is translated into a BIOS drive number. All of these things are relatively easy to do, but it is useless if it is not in the standard LVM code. Mapping from a LV dev_t to an lv_t is simply checking MAJOR(dev) == LVM_MAJOR, return lv[MINOR(dev) + 1] or so. Doing the block remapping is already in lvm_map(), and just needs to be moved into a separate function that can be called via ioctl. Cheers, Andreas