Hi,

The chmod should be

chmod 1777 /dev/shm

ls -alh /dev/shm

total 4.0K

drwxrwxrwt  2 root root   60 Dez 21 12:06 .

drwxr-xr-x 17 root root 5.6K Dez 21 12:06 ..

-rw----rw-  1 root root 4.0K Dez 21 12:06 PHS-5723

That 1 before the 777 sets the sticky bit.

**RESTRICTED****DELETION****FLAG****OR****STICKY****BIT**

The  restricted  deletion  flag  or  sticky  bit is a single bit, whose

interpretation depends on the file type.  For directories, it  prevents

unprivileged  users  from  removing or renaming a file in the directory

unless they  own  the  file  or  the  directory;  this  is  called  the

restricted  deletion  flag  for the directory, and is commonly found on

world-writable directories like **/tmp**.  For regular files on some  older

systems,  the  bit saves the program's text image on the swap device so

it will load more quickly when run; this is called the stickybit.

The sticky bit  plus 777 lets /tmp and /dev/shm work correctly by letting everyone create and delete files, but unless they are root only they can delete only their own files.

It won't fail on a single user system if you just use 777, but, it is a security leak on a multi user system since it lets me manipulate your shared memory segments etc. cheers

bruce

Hi Ken,

thanks for this!! I’ll try and add an error message to the failure to point users to the fix. This is another one like not being able to set the heartbeat thread priority that the vm needs to report as helpfully as possible.

_,,,^..^,,,_ (phone)

...

On Dec 31, 2020, at 6:15 AM, Ken.Dickey@whidbey.com wrote:

Apologies to all, I though I had trimmed the header on this..

-KenD

Message: 6 Date: Thu, 31 Dec 2020 04:18:58 -0800 From: Christoph Thiede To: OpenSmalltalk/opensmalltalk-vm

Cc: Comment , OpenSmalltalk-Bot

Subject: Re: [Vm-dev] [OpenSmalltalk/opensmalltalk-vm] Trouble running OSVM in an Ubuntu 20/aarch64 docker (raspi) (#544) Message-ID:

Content-Type: text/plain; charset="utf-8"

I have tried that and built the VM again, but I keep getting the same mprotect error message :( Any other ideas?

From: oscogvm/build.linux64ARMv8/HowToBuild:

vvv======vvv

If running the resultant squeak vm gives an error something like mprotect(x,y,PROT_READ|PROT_EXEC) or memory_alias_map: shm_open: Permission denied you need to enable shared memory for the COG JIT.

As root: chmod 777 /dev/shm echo 'none /dev/shm tmpfs rw,nosuid,nodev 0 0' >> /etc/fstab mount /dev/shm

The squeak vm should now work. ^^^======^^^