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Diffstat (limited to 'gitlab/issues/target_avr/host_missing/accel_missing/1525.toml')
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1 files changed, 0 insertions, 86 deletions
diff --git a/gitlab/issues/target_avr/host_missing/accel_missing/1525.toml b/gitlab/issues/target_avr/host_missing/accel_missing/1525.toml deleted file mode 100644 index 4ebbc8b7..00000000 --- a/gitlab/issues/target_avr/host_missing/accel_missing/1525.toml +++ /dev/null @@ -1,86 +0,0 @@ -id = 1525 -title = "Wrong initial value of stack pointer on AVR devices" -state = "closed" -created_at = "2023-03-01T15:03:46.130Z" -closed_at = "2023-11-28T23:12:55.240Z" -labels = ["target: avr"] -url = "https://gitlab.com/qemu-project/qemu/-/issues/1525" -host-os = "Windows 11 22H2" -host-arch = "AMD64" -qemu-version = "v7.2.0-11948-ge6523b71fc-dirty" -guest-os = "None" -guest-arch = "AVR" -description = """The initial value of stack pointer of AVR MCUs should be RAMEND (address of the end of their RAM), but QEMU initialize them to 0. - -`qemu-system-avr -machine help` lists 4 flavors of MCUs which are ATmega168, ATmega2560, ATmega1280, ATmega328P. According to their datasheets, the stack pointer should be initialized as follows on reset. - -- [ATmega168](https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-9365-Automotive-Microcontrollers-ATmega88-ATmega168_Datasheet.pdf#page=12): RAMEND (which is 0x04FF) -- [ATmega2560 and ATmega1280](https://ww1.microchip.com/downloads/en/devicedoc/atmel-2549-8-bit-avr-microcontroller-atmega640-1280-1281-2560-2561_datasheet.pdf#page=15): RAMEND (which is 0x21FF) -- [ATmega328P](https://ww1.microchip.com/downloads/aemDocuments/documents/MCU08/ProductDocuments/DataSheets/ATmega48A-PA-88A-PA-168A-PA-328-P-DS-DS40002061B.pdf#page=22): RAMEND (which is 0x08FF)""" -reproduce = """1. Assemble the assembly code below: `avrasm2 -fI test.asm` - - ```asm - ;; test.asm - .INCLUDE "m328Pdef.inc" - - .EQU F_CPU = 16000000 - .EQU BAUD_RATE = 9600 - .EQU PRESCALE = (F_CPU / (16 * BAUD_RATE)) - 1 - - .CSEG - start: - \t;; initialize USART (serial port) - \tLDI R16, LOW(PRESCALE) - \tLDI R17, HIGH(PRESCALE) - \tSTS UBRR0L, R16 - \tSTS UBRR0H, R17 - \tLDI R16, (1 << RXEN0) | (1 << TXEN0) - \tSTS UCSR0B, R16 - - \t;; Get stack pointer low byte and print it in ASCII - \tIN R16, SPL - \tLDI R17, 0x30 - \tADD R16, R17 - print1: - \tLDS r17, UCSR0A - \tSBRS r17, UDRE0 - \tRJMP print1 - \tSTS UDR0, r16 - - \t;; Get stack pointer high byte and print it in ASCII - \tIN R16, SPH - \tLDI R17, 0x30 - \tADD R16, R17 - print2: - \tLDS r17, UCSR0A - \tSBRS r17, UDRE0 - \tRJMP print2 - \tSTS UDR0, r16 - - end: - \tRJMP end - ``` - -2. Convert it to bin file: `avr-objcopy --input-target=ihex --output-target=binary test.hex test.bin` - -3. Run it with QEMU: `qemu-system-avr -machine uno -bios test.bin -serial stdio` - -This should print 00 which means that the stack pointer is initialized to 0.""" -additional = """I examined the source code and I think that editing the function `avr_cpu_reset_hold` in `/target/avr/cpu.c` might fix this issue. This is my first time seeing QEMU source code, so I might be wrong, though. - -```c -// in /target/avr/cpu.c line 70 -static void avr_cpu_reset_hold(Object *obj) -{ - // ... - - env->rampD = 0; - env->rampX = 0; - env->rampY = 0; - env->rampZ = 0; - env->eind = 0; - env->sp = 0; // <-- change this value in accordance with board type? - - //... -} -```""" |