Use register g6 for the per-CPU control of the current processor. The
register g6 is reserved for the operating system by the SPARC ABI. On
Linux register g6 is used for a similar purpose with the same method
since 1996.
The register g6 must be initialized during system startup and then must
remain unchanged.
Since the per-CPU control is used in all critical sections of the
operating system, this is a performance optimization for the operating
system core procedures. An additional benefit is that the low-level
context switch and interrupt processing code is now identical on non-SMP
and SMP configurations.
The registers g2 through g4 are reserved for applications. GCC uses
them as volatile registers by default. So they are treated like
volatile registers in RTEMS as well.
The _CPU_Context_switch() is a normal function call. The following
registers are volatile (the caller must assume that the register
contents are destroyed by the callee) according to "SYSTEM V APPLICATION
BINARY INTERFACE - SPARC Processor Supplement", Third Edition: g1, o0,
o1, o2, o3, o4, o5. Drop these registers from the context.
Ensure that offset defines match the structure offsets.
_CPU_Context_switch_to_first_task_smp() branches to
done_flushing which requires o3 to be initalized with
"self per-CPU control", this adds initialization of
o3. This problem only affects SMP, see commit
f8ad6c6f7f were usage of o3 was intruduced.
Move the _CPU_Context_switch(), _CPU_Context_restore() and
_CPU_Context_switch_to_first_task_smp() code since the method to obtain
the processor index is BSP specific.
As a side-effect the PR2082 is fixed with this and later changes.
The commit restores the _ISR_Handler code to the original version in
"cpukit/score/sparc/cpu_asm.S" in commit
6d42b4c60a. A list of reverted changes
follows.
commit c236082873
Author: Sebastian Huber <sebastian.huber@embedded-brains.de>
Date: Tue Jul 30 15:54:53 2013 +0200
smp: Provide cache optimized Per_CPU_Control
Delete _Per_CPU_Information_p.
This commit was completely reverted.
commit e517714b7c
Author: Jennifer Averett <jennifer.averett@oarcorp.com>
Date: Tue Feb 26 12:31:23 2013 -0600
sparc: Remove dead code that was leftover from SMP development.
This commit was completely reverted.
commit 47a61aa16f
Author: Joel Sherrill <joel.sherrill@OARcorp.com>
Date: Fri Oct 7 14:35:03 2011 +0000
2011-10-07 Daniel Hellstrom <daniel@gaisler.com>
PR 1933/cpukit
* shared/irq_asm.S: From code inspection I have found the following
issues (most SMP), and some improvements in irq_asm.S. I would need a
long test with interrupts to verify the interrupt handler better,
however I can not see that these patches hurt. Please see comment per
hunk below, One should go through the file to indent delay-slots
correctly, I have fixed some in the patch areas. An extra space is
added in front of delay slots to indicate a delay slot.
This commit was completely reverted.
commit 0bd3f7e5d1
Author: Jennifer Averett <Jennifer.Averett@OARcorp.com>
Date: Thu Jul 28 17:33:07 2011 +0000
2011-07-28 Jennifer Averett <Jennifer.Averett@OARcorp.com>
PR 1801
* shared/irq_asm.S: Modifications to synch the sparc with the smp
working tree.
This commit was completely reverted.
commit 5d69cd33e9
Author: Joel Sherrill <joel.sherrill@OARcorp.com>
Date: Wed Mar 16 20:05:30 2011 +0000
2011-03-16 Jennifer Averett <jennifer.averett@OARcorp.com>
PR 1729/cpukit
* shared/irq_asm.S: New file.
The parts modifying the original code of _ISR_Handler were reverted.
Only the content move remains.
Script does what is expected and tries to do it as
smartly as possible.
+ remove occurrences of two blank comment lines
next to each other after Id string line removed.
+ remove entire comment blocks which only exited to
contain CVS Ids
+ If the processing left a blank line at the top of
a file, it was removed.
PR 1933/cpukit
* shared/irq_asm.S: From code inspection I have found the following
issues (most SMP), and some improvements in irq_asm.S. I would need a
long test with interrupts to verify the interrupt handler better,
however I can not see that these patches hurt. Please see comment per
hunk below, One should go through the file to indent delay-slots
correctly, I have fixed some in the patch areas. An extra space is
added in front of delay slots to indicate a delay slot.
