http://longhouse.vikings.scot/uefi/foundation_model-line_in_sand.html ARM, open source and stuff... en http://blogs.law.harvard.edu/tech/rss blosxom/2.1.2 Sat, 09 Aug 2014 23:16:00 +0100 http://longhouse.vikings.scot/2014/08/09#foundation_model-line_in_sand /uefi http://longhouse.vikings.scot/uefi/foundation_model-line_in_sand When <a href="http://www.arm.com/">ARM</a> announced its 64-bit architecture, this was eventually followed by a free (as in beer) software model of that architecture. This model is called the Foundation Model, and although somewhat of an unwanted stepchild next to the commercially available (read <i>expensive</i>) FVP Base model, it is periodically updated. <p/>Unfortunately, these updates are not just feature additions and bugfixes - there have also been substantial changes to the platform in the shape of memory map modifications and the introduction of GICv3 support. <p/>And finally, on the platform software side, both support for UEFI and <a href="https://github.com/ARM-software/arm-trusted-firmware">ARM Trusted Firmware</a> were added substantially later than the Foundation Model was released. And they have changed over time to accomodate the changes in the model. <p/>What this means is that it has not been possible to keep a stable development platform while also being able to update model versions and firmware. I think what is needed is to draw a line in the sand not too far back and make sure <i>everyone</i> developing on the Foundation Model use a minimum version of everything, and a standardised configuration. That is what I am trying to provide with this post. <p/>But aside from complaining, there has also been various software features added that in themselves motivate an upgrade in order to simplify doing the right thing. <h3>So, where is that line?</h3> My suggestion is that the line is drawn as follows: <table> <tr> <th>Component</th> <th>Version</th> <th>Reason</th> </tr> <tr> <td>Foundation Model</td> <td>0.8.5206</td> <td>bugfixes, latest memory map</td> </tr> <tr> <td>ARM Trusted Firmware</td> <td>v0.4</td> <td>New-ish?</td> </tr> <tr> <td>UEFI</td> <td>Linaro-edk2 2014.06, or corresponding upstream</td> <td>Fixes for making efibootmgr functional from within Linux. Linaro build includes a built-in DTB.</td> </tr> <tr> <td>Linux Kernel</td> <td>v3.16</td> <td>UEFI support available for arm64 in upstream kernel</td> </tr> </table> <p/>Furthermore, in order for this all to work, Foundation Model must be called with <code>--gicv3</code>, or UEFI will fail to boot properly. Also, the DTB provided with mainline Linux does not function at all with modern versions of the model. If you don't use a UEFI image that provides you with one, the only place you can find one is in the ARM Trusted Firmware tree, under 'fdts/'. <code>fvp-foundation-gicv2-psci.dtb</code> is a safe bet (since the GICv3 implementation is backwards compatible). <p/>If you want to use GRUB, 2.02~beta2 contains full support for arm64 UEFI platforms.