Debian 64t transition causes build failure on 32bit arch

[Peter Van Eynde]

Hi,

During a rebuild of sbcl 2.3.7 on Debian/unstable, after the https://wiki.debian.org/ReleaseGoals/64bit-time transition, we see a problem for armhf. See https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1069520

> "obj/from-xc/src/code/late-globaldb.lisp-obj"
>
> debugger invoked on a TYPE-ERROR:
> The value
> 542868266893180929
> is not of type
> (UNSIGNED-BYTE 32)
> when setting slot SB-THREAD::OBSERVED-INTERNAL-REAL-TIME-DELTA-SEC of structure SB-THREAD:THREAD
...
> (GET-INTERNAL-REAL-TIME)
> 0]

This seems to be related to the 64t change as when I try to rebuild on armhf I see a change in the grovelled data:

(sid_armhf-dchroot)pvaneynd@abel:~/sbcl-2.3.7$ diff -u ./crossbuild-runner/backends/arm/stuff-groveled-from-headers.lisp output/stuff-groveled-from-headers.lisp
--- ./crossbuild-runner/backends/arm/stuff-groveled-from-headers.lisp 2023-07-29 07:59:39.000000000 +0000
+++ output/stuff-groveled-from-headers.lisp 2023-07-29 07:59:39.000000000 +0000
@@ -30,7 +30,7 @@
 (define-alien-type off-t (signed 64))
 (define-alien-type size-t (unsigned 32))
 (define-alien-type ssize-t (signed 32))
-(define-alien-type time-t (signed 32))
+(define-alien-type time-t (signed 64))
 (define-alien-type suseconds-t (signed 32))
 (define-alien-type uid-t (unsigned 32))
 ;; Types in src/runtime/wrap.h. See that file for explantion.
@@ -141,6 +141,7 @@
 (defconstant clock-process-cputime-id 2) ; #x2
 (defconstant clock-realtime-alarm 8) ; #x8
 (defconstant clock-realtime-coarse 5) ; #x5
+(defconstant clock-tai 11) ; #xb
 (defconstant clock-monotonic-coarse 6) ; #x6
 (defconstant clock-monotonic-raw 4) ; #x4
 (defconstant clock-boottime 7) ; #x7
@@ -149,11 +150,11 @@
 ;;; structures
 (define-alien-type nil
   (struct timeval
- (tv-sec (signed 32))
- (tv-usec (signed 32))))
+ (tv-sec (signed 64))
+ (tv-usec (signed 64))))
 (define-alien-type nil
   (struct timespec
- (tv-sec (signed 32))
+ (tv-sec (signed 64))
           (tv-nsec (signed 32))))

I think we need to change

❯ git grep observed-internal-real-time-delta-sec
src/code/thread-structs.lisp: #-64-bit (observed-internal-real-time-delta-sec 0 :type sb-vm:word)
src/code/unix.lisp: (sb-thread::thread-observed-internal-real-time-delta-sec thr))

to account for the 64bit nature of tv-sec and friends, even on 32 bit architectures.

Best regards, Peter

[Douglas Katzman (dougk)]

The easiest solution may be to put some C code in wrap.c that returns a timespec the way lisp expects it to look because I don't see anything in the Lisp side that seems wrong. Nanoseconds are immediately scaled down by 10^6 after calling clock_gettime so that get-internal-real-time remains a fixnum. Therefore anything stored in the 'observed-delta' slot should not be too large.
I'll bet it's a discrepancy in what Lisp thinks a 64-bit integer looks in a C structure in this ABI (is it most-significant half first or second? I don't know). I see no other instance where Lisp cared about that for a 32-bit build. A few kernel types were 64-bit already, but none of them very interesting to Lisp: dev_t, ino_t for example

[Sean Whitton (spwhitton)]

Hello,

The error output is slightly different with sbcl 2.4.5 but it would seem to be the same bug:

    "obj/from-xc/src/code/late-globaldb.lisp-obj"
    Internal error #88 "Object is not of type UNSIGNED-BYTE-32." at 0x4f859610
 SC: 0, Offset: 0 $1= 0x51267e0f: other pointer
    fatal error encountered in SBCL pid 31092:
    internal error too early in init, can't recover

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