There is currently a big problem in the address environment handling which
is that the address environment is released too soon when the process is
exiting. The current MMU mappings will always be the exiting process's, which means
the system needs them AT LEAST until the next context switch happens. If
the next thread is a kernel thread, the address environment is needed for
longer.
Kernel threads "lend" the address environment of the previous user process.
This is beneficial in two ways:
- The kernel processes do not need an allocated address environment
- When a context switch happens from user -> kernel or kernel -> kernel,
the TLB does not need to be flushed. This must be done only when
changing to a different user address environment.
Another issue is when a new process is created; the address environment
of the new process must be temporarily instantiated by up_addrenv_select().
However, the system scheduler does not know that the process has a different
address environment to its own and when / if a context restore happens, the
wrong MMU page directory is restored and the process will either crash or
do something horribly wrong.
The following changes are needed to fix the issues:
- Add mm_curr which is the current address environment of the process
- Add a reference counter to safeguard the address environment
- Whenever an address environment is mapped to MMU, its reference counter
is incremented
- Whenever and address environment is unmapped from MMU, its reference
counter is decremented, and tested. If no more references -> drop the
address environment and release the memory as well
- To limit the context switch delay, the address environment is freed in
a separate low priority clean-up thread (LPWORK)
- When a process temporarily instantiates another process's address
environment, the scheduler will now know of this and will restore the
correct mappings to MMU
Why is this not causing more noticeable issues ? The problem only happens
under the aforementioned special conditions, and if a context switch or
IRQ occurs during this time.
Detach the address environment handling from the group structure to the
tcb. This is preparation to fix rare cases where the system (MMU) is left
without a valid page directory, e.g. when a process exits.
ld: warning: boards/arm/rp2040/raspberrypi-pico-w/scripts/raspberrypi-pico-flash.ld contains output sections; did you forget -T?
Signed-off-by: chao an <anchao@xiaomi.com>
common/arm_backtrace_unwind.c: In function 'up_backtrace':
common/arm_backtrace_unwind.c:626:27:
warning: assignment to 'long unsigned int' from 'uint8_t (*)[]'\
{aka 'unsigned char (*)[]'} makes integer from pointer without a cast [-Wint-conversion]
626 | frame.stack_top = &g_intstacktop;
|
In order to make compilation warnings and errors easier to be found out,
this commit will disable the printing of the compilation process as much
as possible, and also if you want to restore the log information of the
compilation process, please enable verbose build on command line:
$ make V=0
OR
$ make V=1
| V=0: Exit silent mode
| V=1,2: Enable echo of commands
| V=2: Enable bug/verbose options in tools and scripts
Signed-off-by: chao an <anchao@xiaomi.com>
NuttX kernel should not use the syscall functions, especially after
enabling CONFIG_SCHED_INSTRUMENTATION_SYSCALL, all system functions
will be traced to backend, which will impact system performance.
Signed-off-by: chao an <anchao@xiaomi.com>
This is a follow-up to PR #6548, which added UART CTS/RTS support for
Tiva (TI TM4C12x) microcontrollers. This follow-up makes it possible,
when termios support is enabled with CONFIG_SERIAL_TERMIOS and CTS/RTS
support is enabled with CONFIG_SERIAL_OFLOWCONTROL and/or
CONFIG_SERIAL_IFLOWCONTROL, to query whether CTS/RTS are on/off at
runtime by utilizing ioctl TCGETS and to turn CTS/RTS on/off at runtime
by utilizing ioctl TCSETS.
* arch/arm/src/tiva/common/tiva_serial.c
(up_set_format): Because this function is called from ioctl TCSETS to
modify UART settings, and that IOCTL now respects CCTS_OFLOW and
CRTS_IFLOW, move setting/clearing of Tiva UART's CTL register's RTSEN
and CTSEN bits here...
(up_setup): ...from here.
(up_ioctl): For TCGETS, populate CCTS_OFLOW and CRTS_IFLOW bits as
appropriate. For TCSETS, populate priv's oflow and iflow from
supplied CCTS_OFLOW and CRTS_IFLOW bits.
Thanks to Petro Karashchenko for review and suggested fixes.
Co-authored-by: Petro Karashchenko <petro.karashchenko@gmail.com>
The lower-half serial driver for Tiva (TI TM4C12x) microcontrollers supports
termios, but Kconfig never enabled this support because we were missing the
ARCH_HAVE_SERIAL_TERMIOS configs. This is now enabled, allowing termios support
to be enabled with CONFIG_SERIAL_TERMIOS.
* arch/arm/src/tiva/Kconfig
(config TIVA_UART0 thru TIVA_UART7): Select ARCH_HAVE_SERIAL_TERMIOS.
PWM driver for multiple peripherals supplied in gateware.
Only single channel frequency and duty cycle control is implemented. Pulse counting and multichannel features are not currently feasible.
Additions also include a new board configuration for arty-a7 which enables the PWM driver and example application.
