> On 27. Jul 2024, at 01:20, Bryce <[email protected]> wrote: > > Toomas, you mentioned that you can "script" booting from the unformatted > disk... could you elaborate on this?
since loader is using forth as command interpreter and we have forth words to open, close, read from files, so we can do something like open “disk0p1:” and then read data from it. > > Im aware of the sector zero (mbr or vbr) limitations, so i underatand that > stage 1 must be loaded using bios int 13h. But what about stage 1 loading > stage 2? could you point me to the relevant loop in stage 1 that deals with > passing control to stage 2? specifically, how stage 1 finds stage 2 on disk? > we are just recording starting lba and size in sectors in pmbr binary and it is reading those blocks into memory and jumps there. See usr/src/boot/i386/pmbr/pmbr.s. The values are set by installboot program. To avoid browsing partition tables to guess where our rootfs might be, installboot also does record the lba of rootfs partition in next stage. rgds, toomas > Thanks > > On Fri, Jul 26, 2024, 4:39 PM Toomas Soome via illumos-discuss > <[email protected] <mailto:[email protected]>> wrote: >> >> >> > On 26. Jul 2024, at 22:16, Joshua M. Clulow via illumos-discuss >> > <[email protected] <mailto:[email protected]>> wrote: >> > >> > >> > We actually don't use our legacy GRUB anymore. It hasn't been deleted >> > from the source tree, but it will eventually be when someone finds >> > time to do that gracefully. Our current boot loader is in the tree >> > under "usr/src/boot", and is one we imported from FreeBSD. I don't >> > believe that loader can read directly from a disk slice, but it does >> > have support for several file systems including pcfs (aka FAT), hsfs >> > (aka ISO), UFS, ZFS, etc. >> > >> >> reading from “raw” disk is nothing impossible - we can actually even script >> it, but it is another question, why…. With BIOS setup, we actually read >> stage1 (gptzfsboot) from either boot slice or from zfs label boot block >> area, and the reason is, stage0 is small an can not have file system driver >> built in (we can use 446 bytes max;). The cost of it is that you have to >> have infrastructure to install and maintain your program in raw disk space… >> >> rgds, >> toomas >> > > illumos <https://illumos.topicbox.com/latest> / illumos-discuss / see > discussions <https://illumos.topicbox.com/groups/discuss> + participants > <https://illumos.topicbox.com/groups/discuss/members> + delivery options > <https://illumos.topicbox.com/groups/discuss/subscription>Permalink > <https://illumos.topicbox.com/groups/discuss/Tc9bfa679c7294ee7-Mf77ff3bfd58e2fa6e6b04724> ------------------------------------------ illumos: illumos-discuss Permalink: https://illumos.topicbox.com/groups/discuss/Tc9bfa679c7294ee7-M8a383c71a51fe01800536ffe Delivery options: https://illumos.topicbox.com/groups/discuss/subscription
