Basicaly, that's how i develop it.
There is scripts to load all the images into memory from the JTAG, and make linux boot, this avoid having to manipulate the SDCARD
There is scripts to load all the images into memory from the JTAG, and make linux boot, this avoid having to manipulate the SDCARD
thanks
@lawrie Looking into
https://code.woboq.org/qt5/include/bits/statx.h.html
(quite helpfully, if one hovers over a struct field a popup appears with the byte offset). The offset of the file size field is 40 though - as you have it. I am not quite sure that you have the mask argument correct: value zero requests no fields to be filled in, I think you need the value 0x7FF here. Maybe the kernel infers that when 0 is specified.
statx a bit more. I think that the structure currently is exactly 256 bytes in length, as per the definition here:https://code.woboq.org/qt5/include/bits/statx.h.html
(quite helpfully, if one hovers over a struct field a popup appears with the byte offset). The offset of the file size field is 40 though - as you have it. I am not quite sure that you have the mask argument correct: value zero requests no fields to be filled in, I think you need the value 0x7FF here. Maybe the kernel infers that when 0 is specified.
All that does not explain the crash without exit(0). Maybe there is still a dormant issue with printf. Do you get the same crash if you use sprintf + write? If that works okay, we need to search for a stack corruption issue with printf.
I am currently putting a lot of trivial system calls into syscall.s.
fork and kill are a bit tricky. I think risc-v linux just has clone and execve.
Lots of things only have the "at" versions.
Lots of things only have the "at" versions.
That makes sense. The "at" versions are the newer and more generic ones and when moving to a new platform there is a lot of scope to clean up: as there is not a huge installed base of binaries to support, lot's of stuff can be moved to wrappers and the syscall list kept short.
I think risc-v linux just has clone and execve.
That makes sense too: clone is variant of fork that can optionally create a new process or a new thread; it is Linux specific. Back in V6 Unix there was no "environment" concept, this was added in V7 and exece appeared next to exec. I guess execve is the core one that supports all other variants as library wrappers.
That makes sense. The "at" versions are the newer and more generic ones and when moving to a new platform there is a lot of scope to clean up: as there is not a huge installed base of binaries to support, lot's of stuff can be moved to wrappers and the syscall list kept short.
I think risc-v linux just has clone and execve.
That makes sense too: clone is variant of fork that can optionally create a new process or a new thread; it is Linux specific. Back in V6 Unix there was no "environment" concept, this was added in V7 and exece appeared next to exec. I guess execve is the core one that supports all other variants as library wrappers.
printf is not giving problems in anything else I have tried.
Looking at the old Unix system calls, I don't know what corresponds to alarm and pause in Linux.
alarm sets a timer and after the timer expires, the process receives a SIGALARM signal. It is used to implement sleep(). Let me see what might fit.
For wait, there is waitid.
This is my current syscall.s - https://github.com/lawrie/riscv32_lcc/blob/master/lcc/bin/libs/stdlib/syscall.s
root@buildroot:~# cat fork_test.c
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
#include <errno.h>
int main() {
int p;
int err;
p = fork();
err = errno;
printf("p = %d\n", p);
printf("errno = %d\n", err);
if (p < 0) {
printf("Fork failed\n");
} else if (p == 0) {
printf("Child process\n");
} else {
printf("Parent process\n");
}
return 0;
}
root@buildroot:~# ./a.out
p = 193
errno = 0
p = 0
errno = 0
Parent process
Child process
Also not sure how to do
stime.
Do you think we need any of those?
The nice() system call adjusts the process priority. On Linux it is a wrapper, using setpriority() and getpriority():
https://linux.die.net/man/2/nice
https://linux.die.net/man/2/getpriority
For the wrapper, read the notes on both man pages. Because valid return codes are -20..+20 and half of that range conflicts with the Linux error code range (-4095..-1) some trickery is involved. Use PRIO_PROCESS for which.
https://linux.die.net/man/2/nice
https://linux.die.net/man/2/getpriority
For the wrapper, read the notes on both man pages. Because valid return codes are -20..+20 and half of that range conflicts with the Linux error code range (-4095..-1) some trickery is involved. Use PRIO_PROCESS for which.
On the syscall list:
- alarm & pause: not needed, nanosleep will do (with wrappers for sleep and usleep)
- mpxchan: a (failed) networking experiment, not relevant.
- chroot: still exists, but perhaps not in the 80% of usage list
- creat & mknod: not needed, these have been rolled into open() flags.
- gtty & stty: not needed, these have been replaced by ioctl(), which you have
- nosys & nullsys: not needed - nosys is a placeholder for calls that have not been included and results in a ENOSYS error (like you saw yesterday) and nullsys is for a call that was silently ignored.
- profil was used for profiling code. Not sure how this works on Linux and can be ignored for now, I think.
- ptrace was the original debugger interface and can be ignored. How this works on Risc-V linux will come back as a topic if we ever do a debugger for lcc code.
- rexit: internal name of exit(); you already have that one
- ssig: sets the signal mask. Signals (at least historically) need a fairly complex support routine in user space to work - I suggest we leave it too later.
- gtime, stime, ftime: gtime is the internal name of time(). stime sets the time, needs root privilege and will be needed for Emard's RTC code, ftime gets time at millisecond resolution and is maybe outside the "80% set".
- sysacct, syslock, sysphys: historical accounting and file locking. Can safely be skipped.
I've been too quick on mknod. I think you will need to include
mkdir and rmdir in the core lcc set. Come to think of it, maybe nice is also not in the 80% of usage set.
I also added an examples directory with my C test code.
not yet updated at Smp
This is my latest syscall.s - https://github.com/lawrie/riscv32_lcc/blob/master/lcc/bin/libs/stdlib/syscall.s
I will add setpriority, getprioriity, mkdir and rmdir.
I don't know what the Linux system calls are for time and stime - perhaps settimeofday, gettimeofday.
@pnru_gitlab Not sure how do do rmdir. I have unlinkat - perhaps that does it.