Re: [Qemu-devel] [PATCH v1 for-2.13 0/4] pc-bios/s390-ccw: Network boot improvements

[Farhan Ali <alifm@linux.ibm.com>]

On 04/18/2018 08:31 AM, Thomas Huth wrote:
> Some patches to improve the network boot experience on s390x:
> 
> First, make sure that we shut down the virtio-net device before jumping
> into the kernel. Otherwise some incoming packets might destroy some of
> the kernel's data if it has not taken over the device yet.
> 
> Then the last two patches add support for loading kernels via
> configuration files - pxelinux-style and .INS-file style. This way
> you don't have to manually glue your ramdisk to your kernel anymore,
> so this should be quite a relieve for all users who want to boot
> Linux via the network.
> 
> The config file parsers have been completely written by myself from
> scratch and only tested with some config files that I came up with
> on my own. So if anybody has some pre-existing pxelinux config files
> already for booting a s390x, I'd appreciate some testing to see whether
> this works as expected for you, too!
> 
> Thomas Huth (4):
>    pc-bios/s390-ccw/net: Split up net_load() into init, load and uninit
>      parts
>    pc-bios/s390-ccw/net: Stop virtio-net device before jumping into the
>      OS
>    pc-bios/s390-ccw/net: Add support for pxelinux-style config files
>    pc-bios/s390-ccw/net: Add support for .INS config files
> 
>   pc-bios/s390-ccw/netboot.mak  |   5 +-
>   pc-bios/s390-ccw/netmain.c    | 312 ++++++++++++++++++++++++++++++++++++++----
>   pc-bios/s390-ccw/virtio-net.c |   8 ++
>   pc-bios/s390-ccw/virtio.c     |  19 ++-
>   pc-bios/s390-ccw/virtio.h     |   3 +
>   5 files changed, 312 insertions(+), 35 deletions(-)
> 


I have tried with pxelinux default config file I had and it worked fine. 
I will try a couple more tests.

Also while going through the code again, I noticed a memory leak in the 
function virtio_net_init, and fixed it. I could send a formal patch for 
it, if you want to queue it as part of this series as I think we might 
have missed 2.12 window?

diff --git a/pc-bios/s390-ccw/virtio-net.c b/pc-bios/s390-ccw/virtio-net.c
index ff7f4da..e83ba08 100644
--- a/pc-bios/s390-ccw/virtio-net.c
+++ b/pc-bios/s390-ccw/virtio-net.c
@@ -61,6 +61,7 @@ int virtio_net_init(void *mac_addr)
          IPL_assert(buf != NULL, "Can not allocate memory for receive 
buffers");
          vring_send_buf(rxvq, buf, ETH_MTU_SIZE + sizeof(VirtioNetHdr),
                         VRING_DESC_F_WRITE);
+        free(buf);
      }
      vring_notify(rxvq);