Grant, Excellent. Some suggestions in-line:
On 07/06/2018 12:26 PM, Grant Likely wrote: > Give some rationale behind EBBR so the reader understands what problem > the specification is intended to solve. > > Signed-off-by: Bill Mills <wmi...@ti.com> > [glikely: made it more verbose to make the intent clear] > Signed-off-by: Grant Likely <grant.lik...@arm.com> Don't know the protocol but signed-off-by and/or reviewed-by me again. > --- > source/chapter1-about.rst | 94 > +++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 94 insertions(+) > > diff --git a/source/chapter1-about.rst b/source/chapter1-about.rst > index b667f1b..cb675d9 100644 > --- a/source/chapter1-about.rst > +++ b/source/chapter1-about.rst > @@ -23,6 +23,100 @@ It leverages the prevalent industry standard firmware > specification of [UEFI]_. > > Comments or change requests can be sent to arm.ebbr-disc...@arm.com. > > +Guiding Principals > +================== s/Principals/Principles/ You carried forward my mistake. Daniel correctly pointed out that we are not talking about a helpful person. > + > +EBBR as a specification defines requirements on platforms and operating > systems, > +but requirements alone don't provide insight into why the specification is > +written the way it is, or what problems it is intended to solve. > +Using the assumption that better understanding of the thought process behind > +EBBR will result in better implementations, this section is a discussion of > the > +goals and guiding principle that shaped EBBR. > + > +This section should be considered commentary, and not a formal part of the > specification. > + > +EBBR was written as a response to the lack of boot sequence standardization > in the embedded system ecosystem. > +As embedded systems are becoming more sophisticated and connected, > +it is becoming increasingly important for embedded systems to run standard OS > +distributions and software stacks, or to have consistent behaviour across a > +large deployment of heterogeneous platforms. > +However, the lack of consistency between platforms often requires > per-platform > +customization to get an OS image to boot on multiple platforms. > + > +A large part of this ecosystem is based on U-Boot and Linux. > +Vendors have heavy investments in both projects and are not interested in > large > +scale changes to their firmware architecture. > +The challenge for EBBR is to define a set of boot standards that reduce the > +amount of custom engineering required, make it possible for OS distributions > to > +support embedded platforms, while still preserving the firmware stack product > +vendors are comfortable with. > +Or in simpler terms, EBBR is designed to solve the embedded boot mess by Instead of: > +migrating existing firmware projects (U-Boot) to a defined standard (UEFI). How about + adding a defined standard (UEFI) to the existing firmware projects (U-boot) More accurate, less scary sounding. Makes it clear you are not changing code bases. Some people still think UEFI is a code base. > + > +However, EBBR is a specification, not an implementation. > +The goal of EBBR is not to mandate U-Boot and Linux. > +Rather, it is to mandate interfaces that can be implemented by any firmware > or > +OS project, while at the same time work with both Tianocore/EDK2 and U-Boot > to > +ensure that the EBBR requirements are implemented by both projects. > +[#EDK2Note]_ > + > +.. [#EDK2Note] Tianocore/EDK2 and U-Boot are highlighted here because at the > + time of writing these are the two most important firmware projects. > + Tianocore/EDK2 is a full featured UEFI implementation and so should > + automatically be EBBR compliant. U-Boot is the incumbant firmware project > + for embedded platforms and has added basic UEFI compliance. > + > +The following guiding principals of the EBBR specification and its > +process: s/principals/principles/ > + > +- Be agnostic about ACPI and Devicetree. > + > + EBBR explicitly does not require a specific system description language. > + Both Devicetree and ACPI are supported. > + While ACPI provides more standardization, Devicetree is preferred in may > embedded > + platforms for its flexibility. > + The Linux kernel supports both equally well, and so EBBR doesn't require > one > + over the other. > + However, it does require the system description to be provided by the > + platform, and that it conform to the relevant ACPI or DT specifications. > + > +- Focus on the UEFI interface, not a specific codebase > + > + EBBR does not require a specific firmware implementation. > + Any firmware project can implement these interfaces. > + Neither U-Boot nor Tianocore/EDK2 are required. > + > +- Design to be implementable and useful today > + > + The drafting process for EBBR worked closely with U-Boot and Tianocore > + developers to ensure that current upstream code will meet the requirements. > + > +- Design to be OS independent > + > + This document uses Linux as an example but other OS's are expected. > + > +- Support multiple architectures > + > + Any architecture can implement the EBBR requirements. > + > + .. note:: > + At the time of writing this document only addresses AArch64, but > AArch32 and others architectures are expected. > + > +- Design for common embedded hardware > + > + EBBR support will be implemented on existing developer hardware. > + Generally anything that has a near-upstream U-Boot implementation should be > + able to implement the EBBR requirements. > + EBBR was drafted with readily available hardware in mind, like the > + Raspberry Pi and BeagleBone families of boards, and it is applicable for > low cost boards (<$10). > + > +- Plan to evolve over time > + > + The first release of EBBR is firmly targeting current embedded hardware. > + Future versions will add capabilities which may tighten the hardware > requirements. > + Daniel asked if we want to drop the "hardware" here. > + However, existing compliant boards will remain compliant. > + > Scope > ===== > This document defines the boot and runtime services that are expected by an > Yes, I like your enhanced version much better and it still has all the points I wanted to make. Thanks, Bill _______________________________________________ boot-architecture mailing list boot-architecture@lists.linaro.org https://lists.linaro.org/mailman/listinfo/boot-architecture