diff options
Diffstat (limited to 'gitlab/issues_text/target_arm/host_missing/accel_missing/459')
| -rw-r--r-- | gitlab/issues_text/target_arm/host_missing/accel_missing/459 | 35 |
1 files changed, 0 insertions, 35 deletions
diff --git a/gitlab/issues_text/target_arm/host_missing/accel_missing/459 b/gitlab/issues_text/target_arm/host_missing/accel_missing/459 deleted file mode 100644 index ab940ce38..000000000 --- a/gitlab/issues_text/target_arm/host_missing/accel_missing/459 +++ /dev/null @@ -1,35 +0,0 @@ -bcm2835_aux (raspi3) fails when the receive FIFO fills up -Description of problem: -When a bare-metal application on the `raspi3` board reads the `AUX_MU_STAT_REG` MMIO register while the device's buffer is at full receive FIFO capacity (i.e. `s->read_count == BCM2835_AUX_RX_FIFO_LEN`) the assertion `assert(s->read_count < BCM2835_AUX_RX_FIFO_LEN)` fails. - -The assertion in question is currently in line 141 of `hw/char/bcm2835_aux.c`: https://gitlab.com/qemu-project/qemu/-/blob/9c2647f75004c4f7d64c9c0ec55f8c6f0739a8b1/hw/char/bcm2835_aux.c#L141 -but in my current QEMU version, it seems that it was in line 140, but I don't think that has any implication on this error. If the below steps to reproduce are followed, the full output of a normal QEMU (no debugging output or anything) is simply: - -```text -$ echo abcdefgh | qemu-system-aarch64 -M raspi3 -kernel kernel8.elf -serial null -serial stdio -qemu-system-aarch64: /build/qemu-71DV4m/qemu-4.2/hw/char/bcm2835_aux.c:140: bcm2835_aux_read: Assertion `s->read_count < BCM2835_AUX_RX_FIFO_LEN' failed. -Aborted (core dumped) -``` - -Notice, that there is nothing really wrong with the implementation, if for instance an application that uses the `AUX_MU_LSR_REG` instead to check whether input is available, everything works as expected. It really seems that just this assertion is wrong. Also notice that the [BCM2835 manual](https://www.raspberrypi.org/app/uploads/2012/02/BCM2835-ARM-Peripherals.pdf) (page 18) explicitly allows values inclusive 8. -Steps to reproduce: -1. write a minimal bare-metal application for aarch64 using below main file -2. compile it with a decent aarch64 compiler, linker script and entry assembly as `kernel8.elf` -3. `echo abcdefgh | qemu-system-aarch64 -M raspi3 -kernel kernel8.elf -serial null -serial stdio` -4. QEMU crashes with the above state assertion error -Additional information: -Minimal bare-metal application (`main.c`): - -```c -#define MMIO_BASE 0x3F000000 -#define AUX_MU_STAT ((volatile unsigned int*)(MMIO_BASE+0x00215064)) - -void main() { - while (1) { - // Just read STAT register to trigger the assertion error - *AUX_MU_STAT; - } -} -``` - -Also see [kernel8.elf.zip](/uploads/b12ae2750d2df1bb8db2701f3145f653/kernel8.elf.zip) for a precompiled version of the above application. |