Re: Installable ARMv8 cross-toolchain
On Sat, Nov 03, 2012, Marek Vasut wrote:
> I need to catch up with you in there ;-) What do you use for a bootloader on
> these armv8 devices?
No bootloader at the moment, but a boot wrapper! ;-)
At the moment, ARMv8 work is mostly on virtual platforms (I guess there
might be some people with expensive FGPAs too); the two virtual
platforms Linaro is using are:
* the free (as in beer) ARMv8 Foundation model ("Foundation")
* the pre-built ARMv8 Versatile Express model ("VE RTSM")
ARM recently published some information on the various models at:
http://www.arm.com/fvp
The two virtual platforms are relatively similar; the main differences
are:
* VE model has a MMC while the Foundation model has an AMBA virtio block
device
* VE has a RTC while Foundation model hasn't
* VE has an AMBA LCD (clcd) while Foundation model hasn't
At least the first difference prevents us from sharing a single Device
Tree with all devices between the two platforms (kernel oops when
starting the Foundation model with the MMC listed or vice-versa).
To boot the platform, a small boot wrapper is combined with the kernel,
device tree, and kernel cmdline into an ELF .axf file for the model to
run.
This page explains how to rebuild kernel + device tree + boot wrapper:
https://wiki.linaro.org/HowTo/BuildArm64Kernel
(the boot wrapper is maintained by Catalin Marinas on git.kernel.org)
The plan is to switch to a full bootloader -- likely Tianocore (UEFI) --
when available as it's painful to have to rebuild the .axf whenever the
kernel or kernel cmdline change, and real hardware wouldn't use a boot
wrapper anyway.
I guess you're asking because you consider an U-Boot port? :-)
Cheers,
--
Loïc Minier
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