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Re: [Xen-devel] [PATCH] pypxeboot bootloader

Tim Deegan wrote:
First impressions: this looks really useful but has a few rough edges
that need to be knocked off.  (I haven't had a chance to try this on a
real machine yet.)

I absolutely agree, this was the first working version and I was aware there were nasties in it.

+for line in udhcplines:
+    s = line.strip()
+    f = s.split()
+    if s[0]=='{' and s[-1]=='}':
+        dhcpinfo=eval(s, {"__builtins__" : {}})
+        for k in dhcpinfo:
+            dhcpinfo[k]=dhcpinfo[k].strip()

Executing the results of programs scares me.  Could you just parse it?

Yes quite. Sorry that was cut-and-paste code so I didn't think about it enough. Will rewrite.

+hexip=commands.getstatusoutput("/usr/bin/gethostip -x "+ipaddr)[1]
This requires syslinux to be installed on the Xen host, and isn't hard to do by hand: "%2.2x%2.2x%2.2x%2.2x" % tuple(map (int, ipaddrlist))
(I'm sure more heavyweight python hackers can correct my style.)

Yes of course I'll change that.

+commandstr="tftp -c get "+servaddr+":pxelinux.cfg/"+hexip
+#print "running command "+commandstr

You'll need to be more careful with temporary file names -- here at
least the filename is unique to the guest (we hope!) but for the kernel
etc., two boots could clash.  Also, you don't seem to remove the
downloaded config files.

Yes that all needs tidying up. Unfortunately the version of tftp I was using didn't actually support "get <remote-file> <local-file>" as advertised which I was initially going to use. I'll have to download to the filename supplied by the server then move to a tmpfile.

On the subject of removing files yes of course I'll remove the config files. Comparing with pygrub, that seems to leave kernels and initrds clogging up /var/lib/xen, and I suppose I'll end up doing the same. I suppose you could set up tmpwatch to clean it up, but it still seems a bit messy.

Expect a new patch soon ...

Dr. Stephen Childs,
Research Fellow, EGEE Project,    phone:                    +353-1-8961797
Computer Architecture Group,      email:        Stephen.Childs @ cs.tcd.ie
Trinity College Dublin, Ireland   web: http://www.cs.tcd.ie/Stephen.Childs

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