sys_dlist_remove: bus fault with CONFIG_NO_OPTIMIZATIONS
|
Christopher Friedt
Hi list, I'm experimenting with Zephyr on the kinetis platform and I am encountering a bus fault while running the "samples/net/sockets/dumb_http_server" example. The bus fault only seems to happen when I have CONFIG_NO_OPTIMIZATIONS=y . And is triggered in sys_dlist_remove(). Logs show: initializing network IPv4 address: xxx.xxx.xxx.xxx Single-threaded dumb HTTP server waits for a connection on port 8080... eth_mcux: Enabled 100M full-duplex mode At this point, I can ping the device, but as soon as I run curl or use a browser to open the static page, there is a bus fault (imprecise data bus error) The PC was at sys_dlist_remove and the LR was in sys_dlist_get. I don't have a full stack trace unfortunately because I'm unable to catch this issue with the debugger at present. It's a bit concerning to me that disabling optimizations would result in a bus fault in such a critical path. Potentially related to atomic operations? I haven't yet inspected the sys_dlist*() code yet, but just wanted to probe the list and see if this is a known issue. Any thoughts? PS: Maybe some suggestions for the documentation in this sample project: User should add/modify samples/net/sockets/dumb_http_server/prj.conf * CONFIG_NET_CONFIG_MY_IPV4_ADDR * CONFIG_NET_CONFIG_MY_IPV4_NETMASK * CONFIG_NET_CONFIG_MY_IPV4_GW
|
|
|
|
Maureen Helm
Hi Christopher, It’s possible that a stack overflowed. Kinetis platforms have a “system MPU” instead of the Arm MPU, and memory access violations trigger a bus fault.
Maureen
From: devel@... <devel@...>
On Behalf Of Christopher Friedt via Lists.Zephyrproject.Org
Sent: Monday, September 30, 2019 7:28 AM To: devel@... Cc: devel@... Subject: [Zephyr-devel] sys_dlist_remove: bus fault with CONFIG_NO_OPTIMIZATIONS
Hi list,
I'm experimenting with Zephyr on the kinetis platform and I am encountering a bus fault while running the "samples/net/sockets/dumb_http_server" example.
The bus fault only seems to happen when I have CONFIG_NO_OPTIMIZATIONS=y . And is triggered in sys_dlist_remove().
Logs show:
initializing network IPv4 address: xxx.xxx.xxx.xxx Single-threaded dumb HTTP server waits for a connection on port 8080... eth_mcux: Enabled 100M full-duplex mode
At this point, I can ping the device, but as soon as I run curl or use a browser to open the static page, there is a bus fault (imprecise data bus error)
The PC was at sys_dlist_remove and the LR was in sys_dlist_get.
I don't have a full stack trace unfortunately because I'm unable to catch this issue with the debugger at present.
It's a bit concerning to me that disabling optimizations would result in a bus fault in such a critical path. Potentially related to atomic operations?
I haven't yet inspected the sys_dlist*() code yet, but just wanted to probe the list and see if this is a known issue.
Any thoughts?
PS:
Maybe some suggestions for the documentation in this sample project:
User should add/modify samples/net/sockets/dumb_http_server/prj.conf
* CONFIG_NET_CONFIG_MY_IPV4_ADDR * CONFIG_NET_CONFIG_MY_IPV4_NETMASK * CONFIG_NET_CONFIG_MY_IPV4_GW
|
|
|
|
Christopher Friedt
Hi Maureen, On Mon., Sep. 30, 2019, 11:26 a.m. Maureen Helm, <maureen.helm@...> wrote:
That's interesting, because now that I think about it, I did have to disable the MPU to even get to main(). Good catch! Do you know if Zephyr has a way to instrument stack usage? Cheers, Chris
|
|
|
|
Christopher Friedt
Hi Maureen / list, On Mon., Sep. 30, 2019, 11:31 a.m. Christopher Friedt, <chrisfriedt@...> wrote:
I just thought I would follow up on-list in case anyone else has a similar issue. So I simply enabled CONFIG_STACK_CANARIES=y because ARMv7-M supports gcc's stack canaries, and found that the "tx_workq" thread indeed did have a stack overflow. Great catch Maureen, and thanks for pointing out that the kinetis MPU is not an actual ARM MPU too. I assumed they were the same originally. Cheers, C
|
|
|