Re: configuring with --with-jvm-variants=minimal,server makes cds disappear in server

[Erik Joelsson]

I would lean towards changing the check from "if any of the variants do 
not support CDS, disable it" to "if any of the variants support CDS, 
enable it". The cds jvm feature is only added to the variants that 
support it anyway.

If you do this, you probably need to figure out how to explicitly only 
generate the archive for the supported jvm variants in Images.gmk too. 
Not sure if the archive is jvm variant dependent or if the layout even 
supports multiple variants. It will likely get messy.

/Erik

On 2020-01-16 08:22, Baesken, Matthias wrote:
Hello, thanks for looking into it .
Should I do a check just looking into single JVM configs,   something like

AC_DEFUN([HOTSPOT_IS_JVM_VARIANT],
[ [ [[ " $JVM_VARIANTS " == " $1 " ]] ] ])

if HOTSPOT_IS_JVM_VARIANT(zero) ||  HOTSPOT_IS_JVM_VARIANT(minimal) ||  
HOTSPOT_IS_JVM_VARIANT(core); then

instead of

AC_DEFUN([HOTSPOT_CHECK_JVM_VARIANT],
[ [ [[ " $JVM_VARIANTS " =~ " $1 " ]] ] ])

if HOTSPOT_CHECK_JVM_VARIANT(zero) ||  HOTSPOT_CHECK_JVM_VARIANT(minimal) ||  
HOTSPOT_CHECK_JVM_VARIANT(core); then


This should  remove the error in case of multi-JVM configs .
Or maybe  the whole check ( if HOTSPOT_CHECK_JVM_VARIANT(zero) ||  
HOTSPOT_CHECK_JVM_VARIANT(minimal) ||  HOTSPOT_CHECK_JVM_VARIANT(core); then 
.... fi )
  might be removed , I see not so much value in it  because  in case one sets 
--enable-jvm-features   directly the check isn’t done .

I opened  bug :

https://bugs.openjdk.java.net/browse/JDK-8237374

JDK-8237374 :  configuring with --with-jvm-variants=minimal,server makes cds 
disappear in server


Best regards, Matthias




This does indeed look like a bug to me. At least at Oracle, we no longer
build any multi JVM configs regularly, so things like this falls through
the cracks.

/Erik

On 2020-01-16 02:18, Baesken, Matthias wrote:
Hello, I noticed the following  strange "feature" (or is it a bug?) .
When  building 2 VM variants in one build  and  using

    --with-jvm-variants=minimal,server

For this, the build works nicely. But I notice that  in the server VM, cds  is
removed.
Instead of

checking if cds should be enabled... yes

I get ( with the following patch that adds tracing)  :

configure: WARNING: ENABLE_CDS set to false because we found a
minimal, core or zero JVM.
checking if cds should be enabled... no
    ...

* JVM features:   minimal: 'compiler1 minimal serialgc'       server: 'compiler1
compiler2 epsilongc g1gc jfr jni-check jvmti management nmt parallelgc
serialgc services vm-structs'
(patch is

--- a/make/autoconf/hotspot.m4  Wed Jan 15 21:20:40 2020 -0800
+++ b/make/autoconf/hotspot.m4  Thu Jan 16 10:24:43 2020 +0100
@@ -528,6 +528,7 @@
    if HOTSPOT_CHECK_JVM_VARIANT(zero) ||
HOTSPOT_CHECK_JVM_VARIANT(minimal) ||
HOTSPOT_CHECK_JVM_VARIANT(core); then
       # ..except when the user explicitely requested it with --enable-jvm-
features
       if ! HOTSPOT_CHECK_JVM_FEATURE(cds); then
         ENABLE_CDS="false"
+      AC_MSG_WARN([ENABLE_CDS set to false because we found a
minimal, core or zero JVM.])
         if test "x$enable_cds" = "xyes"; then
           AC_MSG_ERROR([CDS not implemented for variants zero, minimal,
core. Remove --enable-cds.])
         Fi


Is it expected that  cds goes away in "server"   when  configuring  "--with-
jvm-variants=minimal,server"   ?   Looks like a bug to me,  should it be fixed
(so that cds stays in the server   jvm-feature list) ?

Thanks, Matthias