fd_set is a 32bit array, the max fd number is hardcode to 256:
https://github.com/apache/nuttx/blob/master/include/sys/select.h#L38-L91
it's better to define FD_SETSIZE to OPEN_MAX.
On Sun, Feb 19, 2023 at 9:53 AM Gregory Nutt <spudan...@gmail.com> wrote:
> That is okay. My answer is possibly wrong anyway. OPEN_MAX is the maximum
> number of open files. For the select, the file descriptor set was held in
> a 32-bit bit set so the maximum was 31. But that logic has been redesigned
> and I don’t know how it works now.
>
>
>
> Hopefully, it supports up to OPEN_MAX – 1, otherwise that would be a bug.
>
>
>
> On Sat, Feb 18, 2023 at 7:37 PM KIKUCHI Takeyoshi <
> kiku...@centurysys.co.jp>
> wrote:
>
> > Hi Greg,
> >
> > Sorry, it seems that the same one was delivered late, probably because I
> > sent it with the wrong email source account (not the one I subscribed to
> > the list).
> >
> > best regards,
> > KIKUCHI Takeyoshi
> >
> >
> > On 2023/02/19 9:20, Gregory Nutt wrote:
> > > The maximum number of file descriptors is a constant value provided by
> > > the preprocessor definition OPEN_MAX.
> > >
> > > On 2/16/2023 5:44 PM, KIKUCHI Takeyoshi wrote:
> > >> currently porting the Nim language to NuttX.
> > >> (It has been merged into the Nim devel branch)
> > >>
> > >> When using select/epoll, it is necessary to determine the maximum
> > >> value of file descriptor in order to assign a structure to store the
> > >> fd to be waited in advance.
> > >>
> > >> It is used in this way.
> > >>
> > >> ---------
> > >> proc newSelector*[T](): Selector[T] =
> > >> # Retrieve the maximum fd count (for current OS) via getrlimit()
> > >> var maxFD = maxDescriptors() <---
> > >> # Start with a reasonable size, checkFd() will grow this on demand
> > >> const numFD = 1024
> > >> ...
> > >> for i in 0 ... < numFD:
> > >> result.fds[i].ident = InvalidIdent
> > >> ---------
> > >> (Now I realize that numFD also needs to be switched for NuttX...)
> > >>
> > >> Since the available memory capacity varies from device to device,
> > >> Is there any way to find the best value for each build config?
> > >>
> > >> Porting to FreeRTOS in the Nim language uses the maximum number of
> > >> sockets available, set by the user at build time.
> > >>
> > >> ---------
> > >> var FD_MAX* {.importc: "CONFIG_LWIP_MAX_SOCKETS", header:
> > >> "<lwipopts.h>".} : cint
> > >> ---------
> > >>
> > >> best regards,
> > >> KIKUCHI Takeyoshi
> > >>
> > >
> >
> > --
> > kiku...@centurysys.co.jp
> >
>
