Read and publish firmware time stamps and boot time (was: [systemd-devel] bootloader time on a non-EFI bootloader)

[Paul Menzel]

[CC’ing coreboot, GRUB, SeaBIOS, Syslinux project and Linux kernel]

Am Montag, den 16.03.2015, 11:38 +0100 schrieb Kay Sievers:
> On Mon, Mar 16, 2015 at 11:29 AM, Umut Tezduyar Lindskog wrote:
> > I would like to pass the time it was spent in bootloader to systemd.
> > Is there a kernel command line to pass this information on non EFI
> > bootloader? Or is there an another way?
>
> No, there isn't anything I know of.
>
> The kernel boot protocol should probably be extended to accept a block
> of values to be passed from the loader to the OS, and be exported
> somewhere by the kernel itself to userspace.
>
> Overloading the kernel command line with that does not sound like the
> right approach. We should not support anything like that from systemd.

Could that approach please be discussed with all firmware, payload and
firmware projects? For example, coreboot (and the depthcharge payload
used on Chromebooks and Chromeboxes) already store the time stamps in
its CBMEM, which can be read with the utility `cbmem` with `cbmem -t`
[1] or with GRUB’s `coreboot_boottime` command.

10 entries total:

10:start of ramstage             9
          30:device enumeration            441 (432)
          40:device configuration          95,357 (94,915)
          50:device enable                 99,275 (3,918)
          60:device initialization         109,246 (9,971)
          70:device setup done             181,906 (72,659)
          75:cbmem post                    182,274 (368)
          80:write tables                  182,276 (2)
          90:load payload                  183,873 (1,597)
          99:selfboot jump                 283,779 (99,905)

GRUB also has a `boottime` command outputting times like how long a
module needed to load.

One approach would be, that the Linux kernel has drivers to read the
different implementations on how to store the boot time and then exports
those to userspace.

The other approach, and probably more feasible one, is that all firmware
projects use the same standard/specification.

What is actually needed? Are pairs of

project, stage name, time in milliseconds since start of program

where each project gets assigned a unique ID. Do you need more data?

Thanks,

Paul

[1] http://review.coreboot.org/gitweb?p=coreboot.git;a=blob;f=util/cbmem/cbmem.c...

[syslinux] Read and publish firmware time stamps and boot time

[H. Peter Anvin]

On 04/06/2015 02:13 PM, Paul Menzel via Syslinux wrote:
> > The kernel boot protocol should probably be extended to accept a block
> > of values to be passed from the loader to the OS, and be exported
> > somewhere by the kernel itself to userspace.

We have that, it is called initramfs.  It contains a sequence of binary
blobs, each of which has a string identifier, usually known as a
"filename".  The kernel then presents it to userspace as a "file".

-hpa