Supported Processor Configurations - Revision history

Jcmvbkbc: drop highmem and aliasing cache notes as both are resolved now

2014-10-15T23:31:11Z

drop highmem and aliasing cache notes as both are resolved now

← Older revision		Revision as of 23:31, 15 October 2014
Line 1:		Line 1:
	~~= Software Recommendations =~~

	~~== 128 MB RAM Limit ==~~

	Kernel highmem support has not yet been implemented in the main kernel tree, thus restricting generally usable RAM to the first 128 MB (starting from physical address zero). Implementing kernel highmem support should release this limitation, but it isn't yet clear whether an implementation is practical in the presence of cache aliasing (caches larger than 4 x N kB, for an N-way set-associative cache) on RB-200x release or earlier Tensilica processors.

	= Hardware Recommendations =		= Hardware Recommendations =

Line 18:		Line 12:

	Tensilica's PIF Bridges all support this, but if you are using other bridges, this implementation should be verified.		Tensilica's PIF Bridges all support this, but if you are using other bridges, this implementation should be verified.

	~~== Large RAM with Large Caches ==~~

	Tensilica asks to please contact Tensilica support if you are planning to use or build a linux based system that may require more than 128 MB of main RAM for an Xtensa processor configured with large caches (cache size > 4*N kB, for an N-way set associative cache). There are some system limitations that should be evaluated before proceeding.

Chris at 19:07, 11 November 2013

2013-11-11T19:07:53Z

← Older revision		Revision as of 19:07, 11 November 2013
Line 1:		Line 1:
	= Recommendations =		= Software Recommendations =

	This ~~page~~ contains recommendations, notes, limitations and requirements for the development of hardware systems using Linux-Xtensa. They are oriented more towards hardware designer when they create a new Xtensa processor configuration or design an SOC with Xtensa processors.		== 128 MB RAM Limit ==

			Kernel highmem support has not yet been implemented in the main kernel tree, thus restricting generally usable RAM to the first 128 MB (starting from physical address zero). Implementing kernel highmem support should release this limitation, but it isn't yet clear whether an implementation is practical in the presence of cache aliasing (caches larger than 4 x N kB, for an N-way set-associative cache) on RB-200x release or earlier Tensilica processors.

			= Hardware Recommendations =

			This section contains recommendations, notes, limitations and requirements for the development of hardware systems using Linux-Xtensa. They are oriented more towards hardware designer when they create a new Xtensa processor configuration or design an SOC with Xtensa processors.

	== MMU ==		== MMU ==

Chris: /* MMU */

2013-03-16T01:53:28Z

MMU

← Older revision		Revision as of 01:53, 16 March 2013
Line 5:		Line 5:
	== MMU ==		== MMU ==

	Processor configurations to run Linux should always include MMU ~~support~~. Although Linux also supports MMU-less processors, it is not very well tested and has a lot of pitfalls. If the overhead of an MMU is too big, an alternative open or closed source operating system should be considered.		Processor configurations that run Linux should always include the MMU feature. Although Linux also supports MMU-less processors, it is not very well tested and has a lot of pitfalls. If the overhead of an MMU is too big, an alternative open or closed source operating system should be considered.

	== Atomic Memory Access Support ==		== Atomic Memory Access Support ==

Chris at 18:32, 15 March 2013

2013-03-15T18:32:20Z

← Older revision		Revision as of 18:32, 15 March 2013
Line 1:		Line 1:
	= Recommendations =		= Recommendations =

	~~The following list is~~ oriented more towards hardware designer when they create a new Xtensa processor configuration. ~~They are recommendations for various processor options that can be selected when defining the processor.~~		This page contains recommendations, notes, limitations and requirements for the development of hardware systems using Linux-Xtensa. They are oriented more towards hardware designer when they create a new Xtensa processor configuration or design an SOC with Xtensa processors.


	== MMU ==		== MMU ==

Chris: /* Recommendations */

2013-03-15T18:25:15Z

Recommendations

← Older revision		Revision as of 18:25, 15 March 2013
Line 1:		Line 1:
	= Recommendations =		= Recommendations =

			The following list is oriented more towards hardware designer when they create a new Xtensa processor configuration. They are recommendations for various processor options that can be selected when defining the processor.


	== MMU ==		== MMU ==

Chris at 18:20, 15 March 2013

2013-03-15T18:20:26Z

← Older revision		Revision as of 18:20, 15 March 2013
Line 1:		Line 1:
	= ~~Hardware System Limitations~~ =		= Recommendations =

	~~This page contains recommendations, notes, limitations, and requirements for the development of hardware systems using Xtensa processors running Linux.~~		== MMU ==

	~~= Recommendations =~~		Processor configurations to run Linux should always include MMU support. Although Linux also supports MMU-less processors, it is not very well tested and has a lot of pitfalls. If the overhead of an MMU is too big, an alternative open or closed source operating system should be considered.

	== Atomic Memory Access Support ==		== Atomic Memory Access Support ==

Chris: Hardware Issues moved to Supported Processor Configurations

2013-03-15T17:55:05Z

Hardware Issues moved to Supported Processor Configurations

← Older revision	Revision as of 17:55, 15 March 2013
(No difference)

Marc: Move hardware related issues to this page

2008-12-09T22:01:53Z

Move hardware related issues to this page

New page

= Hardware System Limitations =

This page contains recommendations, notes, limitations, and requirements for the development of hardware systems using Xtensa processors running Linux.

= Recommendations =

== Atomic Memory Access Support ==

For future compatibility with Linux kernel releases for the Xtensa architecture, please include support for the atomic load-conditional-store S32C1I instruction when designing your memory system. The memory system must provide for the atomic update of a memory location by holding off the load until all other transactions are complete, and holding off any other transactions once the atomic operation has started until it has finished.

Tensilica's PIF Bridges all support this, but if you are using other bridges, this implementation should be verified.

== Large RAM with Large Caches ==

Tensilica asks to please contact Tensilica support if you are planning to use or build a linux based system that may require more than 128 MB of main RAM for an Xtensa processor configured with large caches (cache size > 4*N kB, for an N-way set associative cache). There are some system limitations that should be evaluated before proceeding.