[syslinux] problem booting from virtual disk, looking for pointers to the code

Gene Cumm gene.cumm at gmail.com
Thu Feb 22 09:23:06 PST 2018


On Thu, Feb 22, 2018 at 11:23 AM, Chris Friesen via Syslinux
<syslinux at zytor.com> wrote:
> Hi,
>
> I'm booting an qemu VM from a virtual disk.  In the success case the virtual
> console shows something like this:
>
> SYSLINUX 4.05 0x54f93f16 Copyright (C) 1994-2011 H. Peter Anvin et al
> Loading vmlinuz.........
> Loading initramfs.img...................................ready.
> [ 0.000000] Initializing cgroup subsys cpuset
> <etc>
>
>
> In the failure case I'm seeing something like this:
>
> SYSLINUX 4.05 0x54f93f16 Copyright (C) 1994-2011 H. Peter Anvin et al
> Loading vmlinuz.........
> Loading initramfs.img..........
>
>
> and then it takes up to ~100 seconds for the VM to start running.  I suspect
> most of that time was spent trying to load this file.
>
> My assumption is that this is likely an IO problem on the host. Would that
> make sense?

It's most likely although CPU contention can cause similar symptoms.
An 8vCPU VM needs 8 idle cores to have execution time.  How many vCPUs
(vCPU = vSockets * vCoresPerSocket)?  Physical cores (not counting CPU
threading)?

> Also, can someone point me to the code that emits the dots while loading the
> file?

core/runkernel.inc calls dot_pause in core/abort.inc

-- 
-Gene


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