Re: [Qemu-devel] [PATCH 0/5] s390x: network boot
On 20.02.2017 17:01, Alexander Graf wrote: > > > On 20/02/2017 07:43, Thomas Huth wrote: >> On 20.02.2017 15:19, Cornelia Huck wrote: >>> This patchset implements network boot for s390x. You need to build >>> a s390-netboot.img to actually perform the work (not included). >> >> Do you plan to include this into the upstream QEMU repository later, or >> will this stay an external binary? >> >>> Basically, we add support for virtio-net devices into the ipl code >>> and update the ccw bios to handle this as well. >> >> Just out of curiosity: What's the reason for shipping an additional >> binary here? Couldn't it be linked into the ccw bios as well (so that >> it's easier for the user to select a different version with the -bios >> parameter)? > > The "other binary" (s390-netboot.img) is the equivalent of grub or > pxelinux in an x86 network boot environment. That one usually comes from > a different entity and different department :). I'd rather compare the other binary to an option ROM. At this point in time we there's no netboot ROM, but a set of instructions on how to build a netboot binary from a kernel and a ramdisk, the series coverletter contains a brief version of that. > > I haven't looked at the patches in detail, but do they follow the > "normal" PXE boot flow? Do they do a DHCP request, send a proper > Vendor-Class-Identifier for s390x, fetch the binary described by the > "filename" property in the DHCP ack via TFTP from next-server and run > that one then? It's currently not described with that level of detail, but the idea is to skip the step of loading a syslinux equivalent, and to immediately fetch the PXELINUX config file from the TFT next server aka siaddr and load the kernel and ramdisk specified therein. I.e. a simulation of the PXELINUX process is done in a similar fashion to petitboot PXE boot. > > It would be very good to stick to that flow, so that you don't confuse > your network admins :). > > > Alex > -- Mit freundlichen Grüßen/Kind Regards Viktor Mihajlovski IBM Deutschland Research & Development GmbH Vorsitzender des Aufsichtsrats: Martina Köderitz Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen Registergericht: Amtsgericht Stuttgart, HRB 243294
Re: [Qemu-devel] [PATCH 0/5] s390x: network boot
On 20/02/2017 07:43, Thomas Huth wrote: On 20.02.2017 15:19, Cornelia Huck wrote: This patchset implements network boot for s390x. You need to build a s390-netboot.img to actually perform the work (not included). Do you plan to include this into the upstream QEMU repository later, or will this stay an external binary? Basically, we add support for virtio-net devices into the ipl code and update the ccw bios to handle this as well. Just out of curiosity: What's the reason for shipping an additional binary here? Couldn't it be linked into the ccw bios as well (so that it's easier for the user to select a different version with the -bios parameter)? The "other binary" (s390-netboot.img) is the equivalent of grub or pxelinux in an x86 network boot environment. That one usually comes from a different entity and different department :). I haven't looked at the patches in detail, but do they follow the "normal" PXE boot flow? Do they do a DHCP request, send a proper Vendor-Class-Identifier for s390x, fetch the binary described by the "filename" property in the DHCP ack via TFTP from next-server and run that one then? It would be very good to stick to that flow, so that you don't confuse your network admins :). Alex
Re: [Qemu-devel] [PATCH 0/5] s390x: network boot
On 20.02.2017 15:19, Cornelia Huck wrote: > This patchset implements network boot for s390x. You need to build > a s390-netboot.img to actually perform the work (not included). Do you plan to include this into the upstream QEMU repository later, or will this stay an external binary? > Basically, we add support for virtio-net devices into the ipl code > and update the ccw bios to handle this as well. Just out of curiosity: What's the reason for shipping an additional binary here? Couldn't it be linked into the ccw bios as well (so that it's easier for the user to select a different version with the -bios parameter)? Thomas
[Qemu-devel] [PATCH 0/5] s390x: network boot
This patchset implements network boot for s390x. You need to build a s390-netboot.img to actually perform the work (not included). Basically, we add support for virtio-net devices into the ipl code and update the ccw bios to handle this as well. For the first patch (elf loading) I'd like to get an ack. A s390-netboot.img can be built by bundling some shell scripts, busybox and the kexec binary bundled into an initial ramdisk and append that to a kernel image. An existing s390 system can be used as source. The init process can be a simple shell script that mounts a few essential filesystems, like /dev, /proc, /sys, ..., starts a DHCP client (busybox udchpc) and then invokes another script to do the actual network boot. udchpc will invoke the script /usr/share/udhcpc/default.script in response to DHCP server messages to configure interfaces. The sample busybox default.script can be used for that, but needs to also extract the DHCP options like the tftp server address and pass that on to the boot script. The boot script itself has to retrieve the PXELINUX configuration from the tftp server as in [1], then retrieve the remote kernel and initial ramdisk and finally use kexec to boot the network kernel. In a nutshell: 1. Create a skeleton initramfs directory structure 2. Create the init script, the PXE boot scripts and the DHCP default script 3. Copy kexec and its dependencies from the source system into the initramfs 4. Copy virtio network and block modules from the source system into the initramfs 5. Copy the busybox binaries into the initramfs 6. Build the ramdisk (in compressed CPIO format) 7. Concatenate the kernel image and the initial ramdisk 8. Update the 8 bytes at location 66568 with the offset value of the ramdisk in the new binary, and the 8 bytes at location 66576 with the size of the ramdisk. Both values need to be updated in binary, big endian format. [1] http://www.syslinux.org/wiki/index.php?title=PXELINUX#Configuration_filename Cornelia Huck (1): pc-bios/s390-ccw.img: rebuild image Farhan Ali (4): elf-loader: Allow late loading of elf s390x/ipl: Extend S390IPLState to support network boot s390x/ipl: Load network boot image pc-bios/s390-ccw: Use the ccw bios to start the network boot hw/core/loader.c | 17 +++-- hw/s390x/ipl.c | 87 + hw/s390x/ipl.h | 5 ++- hw/s390x/s390-virtio-ccw.c | 3 +- hw/s390x/s390-virtio.c | 2 ++ hw/s390x/s390-virtio.h | 1 + include/hw/elf_ops.h | 13 --- include/hw/loader.h| 13 ++- pc-bios/s390-ccw.img | Bin 26392 -> 26456 bytes pc-bios/s390-ccw/bootmap.c | 8 - pc-bios/s390-ccw/iplb.h| 3 +- pc-bios/s390-ccw/main.c| 20 +++ pc-bios/s390-ccw/virtio.c | 1 + pc-bios/s390-ccw/virtio.h | 1 + 14 files changed, 157 insertions(+), 17 deletions(-) -- 2.11.0
