ARM -- reserve RAM outside of bss or data

Log in or register to post comments
Go To Last Post
6 posts / 0 new
Author
Message
TimWescott
TimWescott's picture
Level: New Member
Joined: Fri. Jun 29, 2018
Posts: 12 View posts
#1
Posted by TimWescott: Sat. Feb 9, 2019 - 02:03 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

So, I know exactly how to do this when the IDE isn't in the way; I just edit the linker ld file and I have a nice day.

 

I want to reserve a word at a specific location for special treatment, either by defining a special segment or by defining the start of memory to be at 0x2000 0004 instead of 0x2000 0000.  (It's for clean bootloader to application communication, BTW).

 

How do I do that in AtmelStudio?

Tim

Tags:

Tools, Atmel Studio (ARM-related)
Last Edited: Sat. Feb 9, 2019 - 08:03 PM
Top
meolsen
meolsen's picture
Level: Site Admin
Joined: Wed. Jul 27, 2011
Posts: 3347 View posts
Location: Microchip, Arizona
Posted by meolsen: Sat. Feb 9, 2019 - 04:11 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Modify the linker script? It should be in your project if I remember correctly.

:: Morten

 

(yes, I work for Atmel, yes, I do this in my spare time, now stop sending PMs)

Top
clawson
clawson's picture
Level: Moderator
Joined: Mon. Jul 18, 2005
Posts: 96488 View posts
Location: (using avr-gcc in) Finchingfield, Essex, England
Posted by clawson: Sat. Feb 9, 2019 - 11:06 AM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Morten is right. Unlike AVR, when you use AS7 for ARM it lists the script as an editable component. Presumably (unlike AVR) it mustn't keep single copies of all the scripts in a core location but must copy them each time a project is created?

Top
js
js's picture
Level: Moderator
Joined: Wed. Mar 28, 2001
Posts: 28994 View posts
Location: Sydney, Australia (Gum trees, Koalas and Kangaroos, No Edelweiss)
Posted by js: Sat. Feb 9, 2019 - 08:03 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Moving to ARM area.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

Top
TimWescott
TimWescott's picture
Level: New Member
Joined: Fri. Jun 29, 2018
Posts: 12 View posts
Posted by TimWescott: Tue. Feb 12, 2019 - 05:19 PM
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks.

Tim

Top
TimWescott
TimWescott's picture
Level: New Member
Joined: Fri. Jun 29, 2018
Posts: 12 View posts
Posted by TimWescott: Tue. Feb 12, 2019 - 05:59 PM (Reply to #5)
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

So, I dug into this a bit, and previous developer dealt with reserving space in .text by editing the linker flags (Project->my_project Properties->ARM/GNU Linker->Miscellaneous->Linker Flags.

 

-Wl,--entry=Reset_Handler -Wl,--section-start=.text=0x1000 -Wl,--cref -mthumb -T../src/ASF/sam0/utils/linker_scripts/samd20/gcc/samd20j16_flash.ld

 

I'm not sure if this is the best way to do it for the RAM.  We need this to be different between production code (which makes room for a bootloader) and debug code (which otherwise doesn't fit in RAM).  For the change I'm contemplating we could just have the spot reserved forever.

Tim

Top