On 27.06.2017 23:40, Thomas Huth wrote: [...] >>> - Is it OK to require loading an .INS file first? Or does anybody >>> have a better idea how to load multiple files (kernel, initrd, >>> etc. ...)? >> It would be nice to support PXE-style boot, because the majority of boot >> servers is set up that way. A straightforward way would be to do a PXE >> emulation by attempting to download a pxelinux.cfg from the well-known >> locations, parsing the content (menu) and finally load the kernel, >> initrd and set the kernel command line as specified there. (I know, but >> you're already parsing the INS-File). > > Please, don't mix up PXE and pxelinux (since you've used both terms in > above paragraph). Assuming that you're only talking about pxlinux config > files... are they that common on s390x already? Using the pxelinux > config file syntax sounds like we would be completely bound to only > loading Linux guests to me, since the boot loader has to know where to > load the initrd and how to patch the kernel so that it can find the initrd. > Using .INS files sounds more flexible to me instead, since you can also > specify the addresses here - so you can theoretically also load other > guest kernels, and that's IMHO the better approach since a firmware > should stay as generic as possible. > In order to be consumable, the network boot should support the most common configurations. I would think that most network boot servers are setup as PXE boot servers using pxelinux configs. It will do no good to tell system administrators to have a totally different setup for s390 boot clients. If the firmware doesn't support it we will have to fall back to provide a Linux-based fat netboot image to the pxelinux handling :-(. >> Alternatively, one could load a single boot image (consisting of kernel >> and initrd concatenated, i.e. the bootable ISO format). This could serve >> as a more potent "stage 2" boot loader. > > Agreed, that's also a common practice when doing network booting. I > guess the firmware could also support both quite easily, direct single > boot images, and .INS files. The latter could be detected via the file > name or with the magic string "* " at the beginning. > >>> - The code from SLOF uses a different coding style (TABs instead >>> of space) ... is it OK to keep that coding style here so we >>> can share patches between SLOF and s390-ccw more easil> >>> - The code only supports TFTP (via UDP) ... I think that is OK for >>> most use-cases, but if we ever want to support network booting >>> via HTTP or something else that is based on TCP, we would need to >>> use something else instead... Should we maybe rather head towards >>> grub2, petitboot or something different instead? >> I don't have an opinion on whether HTTP, FTP, etc is needed, but at some >> point in time it would definitely be cool to have IPv6 support. Not sure >> whether SLOF has that included. > > Yes, IPv6 is included in this networking stack. > > Thomas >
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