String getting truncated across OUT link

[David Bracey via Tech-talk <tech-talk at aps.anl.gov>]

EPICS-BASE 7.0.10

PVXS 1.5.0

Linux version 5.14.0-570.62.1.el9_6.x86_64 (mockbuild at x64-builder03.almalinux.org)

I am trying to use an OUT link to move a string from one IOC to another (lso -> lsi) but the string is getting truncated.

Here are the DB's:

    record(lso, "dbracey:src") {

      field(SIZV, 256)

      field(OUT, {pva:"dbracey:tgt"})

    }

    record(lsi, "dbracey:tgt") {

      field(SIZV, 256)

    }

Both are softIocPVX on the same host (the src IOC gets port 5075, the tgt IOC gets port 37875):

    dbracey@somebox:~$ softIocPVX -d src.db

    INFO: PVXS QSRV2 is loaded, permitted, and ENABLED.

    Starting iocInit

    ############################################################################

    ## EPICS R7.0.10

    ## Rev.

    ## Rev. Date :

    ############################################################################

    iocRun: All initialization complete

    epics>

    dbracey@somebox:~$ softIocPVX -d tgt.db

    INFO: PVXS QSRV2 is loaded, permitted, and ENABLED.

    2026-02-06T13:52:42.521554992 WARN pvxs.tcp.setup Server unable to bind port 5075, falling back to [::]:37875

    Starting iocInit

    ############################################################################

    ## EPICS R7.0.10

    ## Rev.

    ## Rev. Date :

    ############################################################################

    cas WARNING: Configured TCP port was unavailable.

    cas WARNING: Using dynamically assigned TCP port 43047,

    cas WARNING: but now two or more servers share the same UDP port.

    cas WARNING: Depending on your IP kernel this server may not be

    cas WARNING: reachable with UDP unicast (a host's IP in EPICS_CA_ADDR_LIST)

    iocRun: All initialization complete

    epics>

The full string makes it into "dbracey:src" but it is truncated in "dbracey:tgt":

    dbracey@somebox:~$ pvxput dbracey:src "1234567890123456789012345678901234567890123456789X"

    dbracey@somebox:~$ pvxget dbracey:src

    dbracey:src

        value string = "1234567890123456789012345678901234567890123456789X"

        alarm.severity int32_t = 0

        alarm.status int32_t = 0

        alarm.message string = ""

        timeStamp.secondsPastEpoch int64_t = 1770407572

        timeStamp.nanoseconds int32_t = 719494104

        timeStamp.userTag int32_t = 0

        display.description string = ""

    dbracey@somebox:~$ pvxget dbracey:tgt

    dbracey:tgt

        value string = "1234567890123456789012345678901234567890"

        alarm.severity int32_t = 0

        alarm.status int32_t = 0

        alarm.message string = ""

        timeStamp.secondsPastEpoch int64_t = 1770407572

        timeStamp.nanoseconds int32_t = 722877993

        timeStamp.userTag int32_t = 0

        display.description string = ""

Watching the ports with tcpdump shows the full string on the src port, but the truncated string on the tgt port:

    [root@somebox dbracey]# tcpdump -A -i lo port 5075

    <snipped>

    13:59:29.895373 IP somebox.fnal.gov.pvaccess > somebox.fnal.gov.47484: Flags [P.], seq 241:335, ack 133, win 512, options [nop,nop,TS val 1485364043 ecr 1485364043], length 94

    E.../f@.@..-...........|...Y........

    X.....

    X..KX..K..@.V.... ..@....21234567890123456789012345678901234567890123456789X..........G.i....A........

    13:59:29.895417 IP somebox.fnal.gov.47484 > somebox.fnal.gov.pvaccess: Flags [P.], seq 133:203, ack 335, win 512, options [nop,nop,TS val 1485364043 ecr 1485364043], length 70

    E..z..@.@.S..........|..............

    @.....

    X..KX..K....>........ .....21234567890123456789012345678901234567890123456789X

    [root@somebox dbracey]# tcpdump -A -i lo port 37875

    <snipped>

    13:59:29.896946 IP somebox.fnal.gov.37875 > somebox.fnal.gov.35472: Flags [P.], seq 203:287, ack 117, win 512, options [nop,nop,TS val 1485364044 ecr 1485364044], length 84

    E...Pg@.@..5.............(...U......

    N.....

    X..LX..L..@.L.... ..@....(1234567890123456789012345678901234567890..........G.i.............

    13:59:29.896984 IP somebox.fnal.gov.35472 > somebox.fnal.gov.37875: Flags [P.], seq 117:204, ack 287, win 512, options [nop,nop,TS val 1485364044 ecr 1485364044], length 87

    E....U@.@..D.............U...(.`....

    Q.....

    X..LX..L....O........ ......(1234567890123456789012345678901234567890..........G.i.............

Any help would be appreciated.