Re: Size limit on extra argument to xm create

[Mick Jordan <Mick.Jordan@Sun.COM>]

On 09/ 9/09 08:49 PM, Mick Jordan wrote:
> Experimentally there seems to be a 1024 byte limit on the size of the 
> extra parameter to xm create (shades of csh!).
>
> Before I dig in to the code, I'm thought I'd check if this a limit in 
> xm or a more fundamental limit in the Xen guest interface. I can 
> imagine a hard limit of a page in the latter case, but that would be a 
> lot better than 1024.
I was too hasty in attributing this to problems with shell variable 
length limits. There does seem to be a Xen limit of 1024 characters for 
the "extra" argument to "xm create", as shown below. The cmd_line value 
passed to the guest is truncated at 1024. So  my question above holds.

# xm create -c xmconfigs/domain_config_generic 
extra="-XX:+UseVirtualMemory -cp /guestvm/image/GuestVM/bin 
test.java.lang.ArgsTest really_quite_a_long_argument_1 
really_quite_a_long_argument_2 really_quite_a_long_argument_3 
really_quite_a_long_argument_4 really_quite_a_long_argument_5 
really_quite_a_long_argument_6 really_quite_a_long_argument_7 
really_quite_a_long_argument_8 really_quite_a_long_argument_9 
really_quite_a_long_argument_10 really_quite_a_long_argument_11 
really_quite_a_long_argument_12 really_quite_a_long_argument_13 
really_quite_a_long_argument_14 really_quite_a_long_argument_15 
really_quite_a_long_argument_16 really_quite_a_long_argument_17 
really_quite_a_long_argument_18 really_quite_a_long_argument_19 
really_quite_a_long_argument_20 really_quite_a_long_argument_21 
really_quite_a_long_argument_22 really_quite_a_long_argument_23 
really_quite_a_long_argument_24 really_quite_a_long_argument_25 
really_quite_a_long_argument_26 really_quite_a_long_argument_27 
really_quite_a_long_argument_28 really_quite_a_long_argument_29 
really_quite_a_long_argument_30 really_quite_a_long_argument_40 
really_quite_a_long_argument_41 really_quite_a_long_argument_42 
really_quite_a_long_argument_43 really_quite_a_long_argument_44 
really_quite_a_long_argument_45 really_quite_a_long_argument_46 
really_quite_a_long_argument_47 really_quite_a_long_argument_48 
really_quite_a_long_argument_49 really_quite_a_long_argument_50 
really_quite_a_long_argument_51 really_quite_a_long_argument_52 
really_quite_a_long_argument_53 really_quite_a_long_argument_54 
really_quite_a_long_argument_55 really_quite_a_long_argument_56 
really_quite_a_long_argument_57 really_quite_a_long_argument_58 
really_quite_a_long_argument_59 really_quite_a_long_argument_60"

Using config file "./xmconfigs/domain_config_generic".
Started domain GuestVM-mjj
argc 35
  0 GuestVM-mjj
  1 -XX:+UseVirtualMemory
  2 -cp
  3 /guestvm/image/GuestVM/bin
  4 test.java.lang.ArgsTest
  5 really_quite_a_long_argument_1
  6 really_quite_a_long_argument_2
  7 really_quite_a_long_argument_3
  8 really_quite_a_long_argument_4
  9 really_quite_a_long_argument_5
  10 really_quite_a_long_argument_6
  11 really_quite_a_long_argument_7
  12 really_quite_a_long_argument_8
  13 really_quite_a_long_argument_9
  14 really_quite_a_long_argument_10
  15 really_quite_a_long_argument_11
  16 really_quite_a_long_argument_12
  17 really_quite_a_long_argument_13
  18 really_quite_a_long_argument_14
  19 really_quite_a_long_argument_15
  20 really_quite_a_long_argument_16
  21 really_quite_a_long_argument_17
  22 really_quite_a_long_argument_18
  23 really_quite_a_long_argument_19
  24 really_quite_a_long_argument_20
  25 really_quite_a_long_argument_21
  26 really_quite_a_long_argument_22
  27 really_quite_a_long_argument_23
  28 really_quite_a_long_argument_24
  29 really_quite_a_long_argument_25
  30 really_quite_a_long_argument_26
  31 really_quite_a_long_argument_27
  32 really_quite_a_long_argument_28
  33 really_quite_a_long_argument_29
  34 really_quite_a_long_argumen
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