Re: [Qemu-devel] Slow kernel/initrd loading via fw_cfg; Was Re: Hack integrating SeaBios / LinuxBoot option rom with QEMU trace backends

[Avi Kivity <avi@redhat.com>]

On 10/11/2011 11:49 AM, Daniel P. Berrange wrote:
> On Tue, Oct 11, 2011 at 11:39:36AM +0200, Avi Kivity wrote:
> >  On 10/11/2011 11:27 AM, Daniel P. Berrange wrote:
> >  >>   >For comparison I also did a test building a bootable ISO using ISOLinux.
> >  >>   >This required 700 ms for the boot time, which is appoximately 1/2 the
> >  >>   >time reqiured for direct kernel/initrd boot. But you have to then add
> >  >>   >on time required to build the ISO on every boot, to add custom kernel
> >  >>   >command line args. So while ISO is faster than LinuxBoot currently
> >  >>   >there is still non-negligable overhead here that I want to avoid.
> >  >>
> >  >>   You can accept parameters from virtio-serial or some other channel.
> >  >>   Is there any reason you need them specifically as *kernel* command
> >  >>   line parameters?
> >  >
> >  >Well some of the parameters are actually kernel parameters :-) The rest
> >  >are things I pass to the 'init' process which runs in the initrd. When
> >  >this process first starts the only things it can easily access are those
> >  >builtin to the kernel image, so data available from /proc or /sys like
> >  >the /proc/cmdline file. It hasn't even loaded things like the virtio-serial
> >  >or virtio-9pfs kernel modules at this point.
> >  >
> >
> >  It could, if it wanted to.  It's completely custom, yes?
>
> I'm thinking primarily about debug related parameters, which need to be
> used as soon the process starts, not delayed until after we've loaded
> kernel modules at which point the step we wanted to debug is already
> past.

Ah, so there's no issue in regenerating the image if you want to debug.

-- 
error compiling committee.c: too many arguments to function