On 23/11/2021 18:13, Joel Sherrill wrote:
On Tue, Nov 23, 2021 at 9:34 AM Sebastian Huber <sebastian.hu...@embedded-brains.de> wrote:Affected components are the GR712RC, UT699, UT699E, UT700, and LEON3FT-RTAX. Strictly, the workaround is only necessary if the MMU is enabled. Use __FIX_LEON3FT_B2BST to enable the workaround. This is not 100% appropriate, but the best thing we can use to enable the workaround. Close #4551. --- cpukit/score/cpu/sparc/cpu_asm.S | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/cpukit/score/cpu/sparc/cpu_asm.S b/cpukit/score/cpu/sparc/cpu_asm.S index 45d1495af7..04b2b0119f 100644 --- a/cpukit/score/cpu/sparc/cpu_asm.S +++ b/cpukit/score/cpu/sparc/cpu_asm.S @@ -190,6 +190,16 @@ done_flushing: ! Try to update the is executing indicator of the heir context mov 1, %g1 +#if defined(__FIX_LEON3FT_B2BST) + /* + * This is a workaround for GRLIB-TN-0011. Affected components are the + * GR712RC, UT699, UT699E, UT700, and LEON3FT-RTAX. Strictly, the + * workaround is only necessary if the MMU is enabled. Using the + * __FIX_LEON3FT_B2BST is not 100% appropriate, but the best thing we + * can use to enable the workaround. + */ +.align 16 +#endifIs there an assumption on the fill pattern here? If the "move 1, %g1" is executed, it looks like the code will fall into the alignment fill area. If those are not guaranteed to be nops, then what instruction(s) are executed? It probably is a nop but that should be checked and in the comment.
It is filled with nops.
And this is in an SMP conditional section but I am unsure if all of those are multi-core models. What does this errata actually cover? Is it that swap needs to be aligned? And it is just a coincidence that this is only in an SMP build of RTEMS? I'm ok with it but the comments and implicit assumptions need to be enhanced.
This is just the recommended workaround for the errata. The errata is mentioned in the comment. I don't think we should duplicate the errata description in the code.
.Ltry_update_is_executing: swap [%o1 + SPARC_CONTEXT_CONTROL_IS_EXECUTING_OFFSET], %g1 -- 2.31.1 _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
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