SBCL enomem on 686

Hi, I was trying to run SBCL on an older 32-bit laptop, using guix on foreign distro. When I launch SBCL, the REPL dies immediately with this error:

```

os_alloc_gc_space(1,0x9000000,3221225472) failed with ENOMEM

fatal error encountered in SBCL pid 4657 tid 4657:

Can't allocate 0xc0000000 bytes for space 1

```

However, the program does work if I pass in a --dynamic-space-size argument when I launch sbcl. E.g.

```

sbcl --dynamic-space-size 2000

```

So, it seems like some allocation value or define is not being set correctly in the build for 686. SBCL manual only says:

```

‘--dynamic-space-size MEGABYTES’

Size of the dynamic space reserved on startup in megabytes.

Default value is platform dependent.

```

My system information:

```

christopher@q4os-desktop

------------------------

OS: Debian GNU/Linux 10 (buster) i686

Host: CF-30CTQAZBM 001

Kernel: 4.19.0-26-686-pae

Uptime: 21 hours, 54 mins

Packages: 2357 (dpkg), 4 (guix-user)

Shell: bash 5.1.16

Resolution: 1024x768

Terminal: /dev/pts/1

CPU: Genuine Intel L2400 (2) @ 1.667GHz

GPU: Intel Mobile 945GM/GMS, 943/940GML Express

Memory: 219MiB / 3020MiB

```

```

$ guix describe

Generation 2 Feb 12 2024 12:22:05 (current)

guix bb92a4d

repository URL: https://git.savannah.gnu.org/git/guix.git

branch: master

commit: bb92a4d7bc71197a51eea9075387c5313f299085

```

--

? Christopher Howard

? gemini://gem.librehacker.com

? http://gem.librehacker.com

?????? ??? ????? ?? ????? ??? ????

Just noticed, poking around in the debian sid package, that Debian had to explicitly set

```

export SBCL_ARCH=x86

```

For their i386 build. Wonder if that might be relevant here.

--

Christopher Howard

Hi, the problem is with these lines:

```

,@(if (target-ppc32?)

;; 3072 is too much for this architecture.

`("--dynamic-space-size=2048")

`("--dynamic-space-size=3072"))

```

Package definition simply assumes that all non-ppc32 architectures can handle the larger dynamic space, but apparently not x86. Through experiment, I see the largest dynamic space that works on my old laptop is 2810, but 2048 seems like a more sensible number.

--

Christopher Howard