Fix for Raspberry Pi firmware changes (total_mem=1024 and WFE in armstub)

Releases, updates and announcements from the Ultibo team.
User avatar
Ultibo
Site Admin
Posts: 2079
Joined: Sat Dec 19, 2015 3:49 am
Location: Australia

Fix for Raspberry Pi firmware changes (total_mem=1024 and WFE in armstub)

Postby Ultibo » Sun Jul 30, 2017 7:33 am

For some time now Raspberry Pi have been testing a new firmware option to allow access to an additional 16MB of RAM that is otherwise obscured by the mapping of the peripherals region on both the Raspberry Pi 2 and 3. While we found this interesting, there has been no urgent need to access more memory in Ultibo (by default there is over 950MB available after booting) so we have not pursued testing this firmware change (total_mem=1024) up until now.

Yesterday the Raspberry Pi foundation committed a change to the firmware repository which makes this new option the default and so it became necessary to test the change for compatibility with Ultibo, tests showed that the new memory map presented was not compatible with the default page table allocation strategy and required a small change in order to prevent boot failure.

The same commit to the firmware also contained a change to the ARM stub to halt all secondary CPUs using the WFE instruction during boot, this change (while not fatal to Ultibo) also required a small addition to the boot process in order to correctly handle the new behavior.

Changes to Ultibo core have now been committed to address both of these issues, you should note the following:

  • These changes only relate to Raspberry Pi 2 and 3, there is no affect or impact on the Raspberry Pi A, B, A+ ,B+ or Zero
  • These changes apply to firmware dated 29 July 2017 (Revision 597B9B66) or later, in earlier releases the total_mem=1024 option had to be enabled manually
  • The changes to Ultibo core are compatible with both old and new versions of the firmware
  • The additional 16MB can be made available to either the GPU (default) or to Ultibo, see this discussion for further information

For details of how to apply the latest source to your Ultibo core installation and rebuild your run time library see the wiki page Building from Source or watch the Building the RTL video on YouTube.
Ultibo.org | Make something amazing
https://ultibo.org
mark
Posts: 1277
Joined: Mon Oct 03, 2016 2:12 am
Location: Indianapolis, US

Re: Fix for Raspberry Pi firmware changes (total_mem=1024 and WFE in armstub)

Postby mark » Mon Jul 31, 2017 6:56 pm

Ultibo wrote:These changes apply to firmware dated 29 July 2017 (Revision 597B9B66) or later
Garry, I can't seem to find where the firmware is labeled 597B9B66. Thanks, Mark.
User avatar
Ultibo
Site Admin
Posts: 2079
Joined: Sat Dec 19, 2015 3:49 am
Location: Australia

Re: Fix for Raspberry Pi firmware changes (total_mem=1024 and WFE in armstub)

Postby Ultibo » Mon Jul 31, 2017 11:49 pm

mark wrote:I can't seem to find where the firmware is labeled 597B9B66.

I don't think I have ever seen it displayed anywhere in the firmware repository or elsewhere, in Ultibo you just use the FirmwareGetRevision() from the Platform unit, it is also visible on the Platform page in WebStatus.

Because it isn't ever referred to by Raspberry Pi I don't know if it is intended to be displayed in decimal or hex, maybe one makes more sense than the other.
Ultibo.org | Make something amazing
https://ultibo.org
develone
Posts: 274
Joined: Wed Dec 28, 2016 7:40 pm
Location: El Paso Tx USA

Re: Fix for Raspberry Pi firmware changes (total_mem=1024 and WFE in armstub)

Postby develone » Tue Aug 01, 2017 12:35 am

Hi all
Latest commit 92a16f1 a day ago is the first digit of a long number 92a16f14a9bda3b402440eada849fecf79f78859
Hope this helps
Cheers

Return to “Ultibo”

Who is online

Users browsing this forum: No registered users and 3 guests