Re: [Qemu-devel] [RFC PATCH 00/14] Implement network booting directly into the s390-ccw BIOS

[Thomas Huth]

On 27.06.2017 18:50, Farhan Ali wrote:
[...]
>> The patches are still in a rough shape, but before I continue here,
>> I though I'd get some feedback first. Specifically:
>>
>> - This adds a lot of additional code to the s390-ccw firmware (and
>>   the binary is afterwards three times as big as before, 75k instead
>>   of 25k) ... is that still acceptable?
> 
> IMHO 75k is not that huge compared to the Linux based netboot image.

True. I was just surprised that the size was now three times as big as
before, but when you compare it to the huge size of a Linux kernel +
initrd, 75k are of course close to nothing.

>> - 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. ...)?
>>
>> - 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 easily?
>>
>> - 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?
> 
> Can't it be extended to support HTTP boot?

Not so easily, since you need TCP support for this first. And TCP is way
more complex to implement when compared with UDP.

 Thomas