On Wed, 19 Feb 2003, Lucius, Leland wrote: > In case anyone's interested, here's a small kernel patch > that gives you the ability to supply kernel command line parameters > via the PARM parameter of the VM IPL command.
This is great! Works really well. Very effective. One thing that would make it more complete would be to also support LOADPARM, which unlike PARM does have a HW equivalent. I'm thinking maybe append "loadparm=whatever" to the parm line iff a LOADPARM is supplied (by hardware IPL or by VM IPL). The "loadparm=" token would then trigger ... whatever! It's a very zSeries-centric option, but not unlike parm tricks I've seen on other architectures. LOADPARM is only 8 bytes. > http://www.homerow.net/projects/zlinux/vmparms.htm I can't thank you enough for this! I've been using it on a 2.4.19 kernel (31 bit) for several days. I use it to switch to a different root disk, but there are quite a few other scenarios where this is useful. One that comes to mind is stuffing DCSSs. To stuff a DCSS, that is, to fill it with content, you'd need to be able to keep the kernel away from DCSS memory. A good way to do that is to define the DCSS beyond some address and lock the kernel below that point. You can do so with a "mem=" parm, which we now have available via VM IPL PARM. For example, if you have a DCSS defined at 64M, to stuff it defseg mydcss 4000-7FFF ew def stor 128m ipl 1234 clear parm mem=64m ... and the DCSS driver can safely use pages 4000-7FFF. and the kernel should stay below that 64M line and your DCSS driver can write the DCSS content without fear that the kernel might step on it. -- RMT
