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Re: [Patch ARM] Add support for bare-metal cpu initialization on A profile cores.
- From: Richard Earnshaw <rearnsha at arm dot com>
- To: Ramana Radhakrishnan <ramrad01 at arm dot com>
- Cc: "newlib at sourceware dot org" <newlib at sourceware dot org>
- Date: Fri, 20 Sep 2013 14:59:30 +0100
- Subject: Re: [Patch ARM] Add support for bare-metal cpu initialization on A profile cores.
- Authentication-results: sourceware.org; auth=none
- References: <523AFD69 dot 8060701 at arm dot com>
On 19/09/13 14:34, Ramana Radhakrishnan wrote:
> Increasingly we've found the need for a start-up routine required for
> bare-metal applications that need to initialize the mmu and the caches
> for use during hardware bring-up and/or for bare-metal testing on ARM's
> propreitary models as well as allow for semi-hosting to happen at the
> same time. This has been found to be useful in a number of situations
> and this is just the initial patch set required for this to work on A
> profile CPUs. I would recommend that this not be used for earlier cores
> without testing.
> The way this is implemented is by adding a new weak function called
> _rdimon_init_hook that deals with this initialization. I expect this to
> work on newer hardware because our testing involves testing with the AEM
> models that model the newer hardware but I don't have access to any such
> hardware to test this right now.
> The SMP enable bit in the ACTLR is enabled only for A15 and A7 but not
> for any other cores as this is needed only on those cores. We use this
> internally for some of our GCC test runs on our fast models, we've tried
> it in the past to run some simple applications on bare-metal A7 and A15
> This necessitates the use of a new specs file aprofile-ve.specs which
> I've added and provided as an example. I have tested this on an AEM
> model but am confident that this will work just fine on a bare-metal
> board connected via D-Stream or anything that implements the standard
> Angel API.
> If people want to use a different base address for the text section and
> / or for the vectors page in the cpu init code this is available by
> doing --defsym _rdimon_vector_base=FOO or -Ttext_section=BAR . The
> specs file only eases the use for this.
> Tested with an arm-eabi bare-metal GCC multilib build across
> architecture variants, Thumbness and fpu abi variants using the new
> specs file in my baremetal build script and tested with
> --specs=aprofile-ve.specs passed by default in my site.exp - tested on
> AEM VE model internally .
> Ok to apply ?
> <DATE> Matthew Gretton-Dann <email@example.com>
> Ramana Radhakrishnan <firstname.lastname@example.org>
> Greta Yorsh <email@example.com>
> * arm/Makefile.in: Add support for cpu-init directory and add
> * arm/configure.in: Likewise.
> * arm/configure: Regenerate.
> * arm/cpu-init: New directory.
> * arm/cpu-init/Makefile.in: New file.
> * arm/cpu-init/rdimon-aem.S: Likewise.
> * arm/crt0.S: Call _rdimon_init_hook
> * arm/elf-aprofile-ve.specs: New file.