Re: erlang -> asmjit -> mremap questions/bugs

[Valery Ushakov <uwe%stderr.spb.ru@localhost>]

On Wed, Mar 01, 2023 at 15:29:27 +0100, Thomas Klausner wrote:

> It seems the problem is that mmap() in the mremap(2) man page example
> (which was used to implement the asmjit version) is not using
> MAP_SHARED.
> 
> - I'd like to add MAP_SHARED in the mmap() call in the mremap(2) man
>   page example. Is that fine?

Not really.  There are no other processes involved in the example, so
MAP_SHARED makes no sense.


> - Reading mmap(2) it seems that one of MAP_SHARED or MAP_PRIVATE is
>   required, but there is no error if none is provided. Should we change
>   mmap() to return an error in that case?

sys/kern/vfs_vnops.c:

    /*
     * Old programs may not select a specific sharing type, so
     * default to an appropriate one.
     */


> - Why does MAP_PRIVATE (instead of MAP_SHARED) not work?

Are there multiple processes involved in the erlang case?


-uwe