joel.sherrill at OARcorp.com
Sun Sep 21 16:37:34 UTC 2008
Thomas Dörfler wrote:
> during some testing of rtems-4.9-branch I came across a modification
> that was made some time ago: The old Cpu_table field
> "do_zero_of_workspace" was moved to the Configuration table and its
> default initialization is now controlled using a BSP define called
> This is generally ok.
> BUT: according to my grep results, this setting is used only in two BSPs
> now: the arm/rtl22xx, and the powerpc/mvme5500
Sounds like it needs to be taken off of those two.
> I really can't belive, that this setting is NOT required by other BSPs.
> When browsing the various Changelogs (e.g. powerpc/Changelog) , I found
> references that before these changes the default for
> "do_zero_of_workspace" in bootcard.c was TRUE, now it is obviously FALSE
> for most of the BSPs.
You must have missed this in the 4.8 release notes. It was ready
to be changed when 4.7 was branched but it felt too dangerous so
was immediately made the default after branching 4.7. It cut ~80%
off the boot time on the BSPs I measured.
> What did I miss? Why is "do_zero_of_workspace" no longer required for
> most of the BSPs?
Because we worked to ensure that all data fields are initialized
EVERY time an object is created. This eliminated the need to
zero the workspace and depend on that. Plus when you reuse
an object control block, it is not zero the 2nd time around.
> Is this a show-stopper for the 4.9.0 version?
It might have been an issue for 4.8.0 but we have been running
this way a while now.
> Any insights welcome!
> embedded brains GmbH
> Thomas Doerfler Obere Lagerstr. 30
> D-82178 Puchheim Germany
> Tel. : +49-89-18 90 80 79-2
> Fax : +49-89-18 90 80 79-9
> email: Thomas.Doerfler at embedded-brains.de
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Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill at OARcorp.com On-Line Applications Research
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