On Wed, Mar 24, 2021 at 2:08 PM Xiang Xiao <xiaoxiang781...@gmail.com> wrote:
> On Wed, Mar 24, 2021 at 9:18 AM Matias N. <mat...@imap.cc> wrote: > > > > > > > - devise a mechanism to mimic what would be done by OS in KERNEL mode > > (add > > > > > some custom handler to APIs internally using globals, such as getopt, > > that can be > > > > > called either manually by user or by the OS itself when the task is > > started?) > > > The custom handler isn't enough here, because the real problem is we need > the global variables per task/process. > As Greg suggests, we need something like TLS but per task/process not per > thread(e.g. task_getspecific/task_setspecific). > Once the mechanism is done, getopt can be converted to confirm the standard > trivally. > I was looking at this exact issue last week (see comment in https://github.com/apache/incubator-nuttx/pull/3054). The basis for this mechanism exists in the way errno is handled. Perhaps a structure defined for all libc globals added to TLS and a call from the task creation code to initialise it? > > > > > - other? > > The transparent/standard solution is switched to the ELF binary(note: it > doesn't depend on KERNEL mode), and then loses the XIP benefit(huge memory > penalty). But, it's doable to XIP again by combining ELF loader and ROMFS. > Switching to ELF doesn't necessarily help - I encountered the problem loading nsh as an ELF binary in a FLAT built. The globals optarg and optind aren't in libc.csv. They'll be picked up and included in symtab_apps, but those symbols will simply point to the (system) global variables, not a per-task variable. Byron
