Hi Jean-Christophe,
Thanks for sharing your notes; we actually had a call the 26th of
August on Barebox; I don't think the notes from the call were shared,
so I'm sharing them below.
I think much more would have to be discussed, so certainly I suspect
there will be more calls. Grant is probably the guy who will make that
happen.
Cheers,
== Attendees ==
Arnd Bergmann
Shaju Abraham
Matt Waddel
Paul McKenney
Loïc Minier
Robert Schwebel
John Rigby
Grant Likely
Steve Sakoman
Mounir Bsaibes
Dave Martin
Nicolas Pitre (mid-call)
== Minutes ==
* Quick mention of what Linaro is for Robert
* Grant working on defining a boot architecture
* Telling manufacturers what firmware should be doing, where it stops
* Not trying to cover the whole world, but more the fairly common case
* Predictable set of interfaces
* Barebox updates
* Sascha Hauer main maintainer
* Biggest problem was u-boot's architecture; old, full of ifdefs, not well
designed structure
* Pengutronix making a lot of bootloaders for industrial systems
* Trying to be a mini-kernel, with the same coding style, modules etc. BUT
trying to keep it to a minimum
* Why not evolve u-boot instead of forking?
* Wolfgang pushed back when introducing Kconfig, modules etc.
* Not much feedback on the new ideas
* Upstream policy would prevent breakage of old boards; but priority was
fixing the architecture rather than keeping support for hundreds of boards
which they didn't have access to
* Was a bad idea to use the new u-boot
* Is Barebox trying to replace u-boot, or will the two exist together?
* Pengutronix using it because they see it as useful
* Presented at conferences, trying to gain more community around the project
* Why not strip down the kernel down to be a bootloader?
* Some SH4 people do this
* Problem is that it takes longer to boot the kernel
* Will likely remain too slow and too large to be a production bootloader,
since drivers rely on too much functionality
* If the kernel is the bootloader, no need for two sets of drivers
* Need to communicate on upgrade risks in the field, more than how the
bootloader is laid out
* Trying to write common device drivers
* Is there effort to be 100% compatible at the source level with the kernel
drivers?
* Problem is getting rid off the possibility of running user programs?
* Current kexecbooting needs some way of loading the initial kernel from NAND
or whatever
* U-Boot and Barebox don't ship in production; why?
* Pengutronix has industry and automotive customers, and they do ship Barebox
* RedBoot has the same issue -- but there's the copyright assignment as well
* Real devices don't really care about loading the kernel from different
places, or even replacing the kernel
* Size and hence price of flash is also a pressure
* In terms of boot time, managed to boot an init in 326ms on imx35
w/Barebox; can also strip down 30 kB
* Apparently, phone manufacturers are really concerned about speed of boot,
and GPL (even v2) because they don't want to share some changes
* Size impacts speed, so is an indirect constraint
* e.g. allows running on SRAM instead of regular RAM on OMAP
* Good idea to allow upgrading the device tree and the kernel, but not
exposing the bootloader
* Would be nice to unify into a common tree the first and second stage
bootloader
* Is it possible to build a single barebox which supports multiple boards? Is
it relocatable?
* Might be some limitations, Sascha would know
--
Loïc Minier
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