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Violators will be prosecuted for from ; Wed, 28 Jun 2017 08:28:38 +0100 From: Viktor Mihajlovski References: <1498564100-10045-1-git-send-email-thuth@redhat.com> <23ec1642-053c-a15a-c03f-d9e48d1447e7@linux.vnet.ibm.com> Date: Wed, 28 Jun 2017 09:28:34 +0200 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Message-Id: <29018087-c00b-abb2-47e6-4ebfc954ff1f@linux.vnet.ibm.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [RFC PATCH 00/14] Implement network booting directly into the s390-ccw BIOS List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Thomas Huth , qemu-devel@nongnu.org, Christian Borntraeger Cc: Eric Farman , Farhan Ali , Alexander Graf , Jens Freimann , David Hildenbrand 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 bo= ot >> 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, bu= t >> you're already parsing the INS-File). >=20 > 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 confi= g > 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 ini= trd. > 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. >=20 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 kerne= l >> and initrd concatenated, i.e. the bootable ISO format). This could ser= ve >> as a more potent "stage 2" boot loader. >=20 > 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 so= me >> point in time it would definitely be cool to have IPv6 support. Not su= re >> whether SLOF has that included. >=20 > Yes, IPv6 is included in this networking stack. >=20 > Thomas >=20 --=20 Mit freundlichen Gr=C3=BC=C3=9Fen/Kind Regards Viktor Mihajlovski IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martina K=C3=B6deritz Gesch=C3=A4ftsf=C3=BChrung: Dirk Wittkopp Sitz der Gesellschaft: B=C3=B6blingen Registergericht: Amtsgericht Stuttgart, HRB 243294