[U-Boot] [RFC PATCH 0/15] RFC: Add tracing functionality to U-Boot

[Tom Rini]

On Sat, Apr 27, 2013 at 07:17:37PM -0700, Simon Glass wrote:

> This series adds a tracing feature to U-Boot which is useful for
> profiling boot time and other purposes.
> 
> The core trace library relies on standard gcc function instrumentation
> and a microsecond timer which should work correctly on almost any
> architecture. Generic board is used to avoid the need to add the same
> code in multiple places (CONFIG_SYS_GENERIC_BOARD).
> 
> Tracing must be built into the U-Boot image at build time, but can be
> paused and resumed while running. A trace buffer is used to collect
> trace information. This buffer can then be transmitted to a host for
> processing. A host-based processing tool is provided which converts the
> data to the same format used by Linux, and that can be read by the
> pytimechart GUI tool.
> 
> A U-Boot 'trace' command provides access to the trace information,
> including support for writing it to memory in a few forms.
> 
> Support is provided for stopping tracing at the last possible moment in
> the bootm process (just before U-Boot jumps to the OS). This is done with
> a new 'fake go' command, which allows bootm to go through the motions of
> an OS boot without actually committing to it. Once the 'fake go' is
> complete, U-Boot can stop tracing and continue execution to transmit the
> trace information to the host, before jumping to the OS for real.
> 
> The system is tested on sandbox and has previously worked on ARM Tegra
> and Exynos machines. A simple test script is provided for sandbox, along
> with documentation on how to use the feature.
> 
> This feature has been successfully used alongside bootstage to locate
> bottlenecks and reduce overall boot time.
> 
> Because of the bootm changes this series sits on top of the image
> improvements that were done for verified boot. This series is available
> at:
> 
>    http://git.denx.de/u-boot-x86.git
> 
> in branch 'trace'.

I like the concept, implementations seems reasonable.  How far back does
gcc support -finstrument-functions?  Any chance of getting tegra support
at least resurrected (since it uses the generic board framework)?
Thanks!

-- 
Tom
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