- Purpose
- It's a bare-metal study in QEMU (-M virt -cpu cortex-a57)
- How to run
# export PATH inclueding your cross compile tool export PATH=$PATH:/home/ryanyao/work/buildroot-2017.11-rc1/output/host/bin make run - GDB (Terminal 1/2 should be in the same directory.)
Terminal 1: qemu-system-aarch64 -machine virt -cpu cortex-a57 -kernel kernel.elf -nographic -S -s Terminal 2: aarch64-linux-gnu-gdb kernel.elf --tui target remote :1234 - Timer IRQ works. It assert Timer_Handler() every 1 sec.
timer_test gic_v3_initialize() init_gicd() init_gicc() CurrentEL = 0x00000000 00000004 RVBAR_EL1 = 0x00000000 00000000 VBAR_EL1 = 0x00000000 40000000 DAIF = 0x00000000 000003C0 Disable the timer, CNTV_CTL_EL0 = 0x00000000 00000000 System Frequency: CNTFRQ_EL0 = 0x00000000 03B9ACA0 Current counter: CNTVCT_EL0 = 0x00000000 0001BA16 Assert Timer IRQ after 1 sec: CNTV_CVAL_EL0 = 0x00000000 03BB66B6 Enable the timer, CNTV_CTL_EL0 = 0x00000000 00000001 Enable IRQ, DAIF = 0x00000000 00000340 Exception Handler! (AARCH64_EXC_IRQ_SPX) IRQ found: 0x00000000 0000001B timer_handler: Disable the timer, CNTV_CTL_EL0 = 0x00000000 00000000 System Frequency: CNTFRQ_EL0 = 0x00000000 03B9ACA0 Current counter: CNTVCT_EL0 = 0x00000000 03BD40D5 Assert Timer IRQ after 0x00000000 00000001 sec(s): CNTV_CVAL_EL0 = 0x00000000 0776ED75 Enable the timer, CNTV_CTL_EL0 = 0x00000000 00000001 Exception Handler! (AARCH64_EXC_IRQ_SPX) IRQ found: 0x00000000 0000001B timer_handler: Disable the timer, CNTV_CTL_EL0 = 0x00000000 00000000 System Frequency: CNTFRQ_EL0 = 0x00000000 03B9ACA0 Current counter: CNTVCT_EL0 = 0x00000000 0778E288 Assert Timer IRQ after 0x00000000 00000001 sec(s): CNTV_CVAL_EL0 = 0x00000000 0B328F28 Enable the timer, CNTV_CTL_EL0 = 0x00000000 00000001
- GDB can't step into main() if miss lable: main_label in boot.S (commit b72c6a8cc7033a4fed89b57f75826d201466179f)
- (Fixed, 2018/07/19) Timer IRQ doesn't work(commit b72c6a8cc7033a4fed89b57f75826d201466179f)
- We can see CNTV_CTL_EL0[2]:ISTATUS changes, but irq_handler doesn't be called.
- And we also didn't see any changes in ISR_EL1.
- Solved in commit 2aaa0bff7516e84e01acd10d8de64189839d9d51.
- (Fixed, 2018/07/05) It should be some problems in vector_table_el1 in boot.S. If I set "b hang" in other vectors except lower_el_aarch64_irq, the uart outpt will be incorrect or system hang (commit b72c6a8cc7033a4fed89b57f75826d201466179f)
- Root cause should be the stack memory is overlaid. Now, we set stack_top = 0x41000000 to avoid it. (commit c14d653fca24387b5996285f45f0fef2906cb2c9)
- Project
- QEMU
- Makefile
- ARM
- Arm® Compiler armasm User Guide
- Application Note Bare-metal Boot Code for ARMv8-A Processors Version 1.0
- ARM® Architecture Reference Manual ARMv8, for ARMv8-A architecture profile Beta
- ARM® Cortex®-A57 MPCore™ Processor Revision: r1p0 Technical Reference Manual
- ARM® Cortex®-A Series Version: 1.0 Programmer’s Guide for ARMv8-A
- ARM® Generic Interrupt Controller Architecture Specification GIC architecture version 3.0 and version 4.0