[RTEMS Project] #2774: RTEMS loaded by u-boot with dcache, icache and mmu enable does not boot.

RTEMS trac trac at rtems.org
Mon Aug 8 06:31:47 UTC 2016

#2774: RTEMS loaded by u-boot with dcache, icache and mmu enable does not boot.
 Reporter:  chrisj  |      Owner:
     Type:  defect  |     Status:  new
 Priority:  normal  |  Milestone:  4.12
Component:  bsps    |    Version:  4.12
 Severity:  normal  |   Keywords:
 The arm/xilinx_zynq_zedboard does not boot with a recent u-boot built from
 git (b2f1858455e99a91aeafe59ac73c6c047106d5e8). I have tracked the issue
 down to the MMU initialization and I am wondering if there are a few
 issues we need to look at closer. I think RTEMS could handle this case a
 little better and this would improve the ARM support making it more
 resilient to how it is run.

 I have the code booting and running and these are the changes.

 1. In arm_cp15_start_setup_translation_table in arm-cp15-start.h I moved
 the arm_cp15_set_translation_table_base to after the table is created.
 While this is not that important I did find when looking into this problem
 it improved things when I had a call to
 arm_cp15_data_cache_clean_all_levels() before setting the table base. I am
 not sure the cache clear is needed.

 2. In the zynq_setup_mmu_and_cache I detect the MMU being enabled and if
 enabled I:

   uint32_t ctrl = arm_cp15_get_control();

   if ((ctrl & ARM_CP15_CTRL_M) != 0) {
     ctrl &= ~(ARM_CP15_CTRL_C | ARM_CP15_CTRL_I | ARM_CP15_CTRL_M);

 This lets ticker run.

Ticket URL: <http://devel.rtems.org/ticket/2774>
RTEMS Project <http://www.rtems.org/>
RTEMS Project

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