From: Wilm Hoyer <W.Hoyer@dental-vision.de>
To: Michael Paquier <michael@paquier.xyz>, Julien Rouhaud <rjuju123@gmail.com>
CC: "pgsql-hackers@lists.postgresql.org" <pgsql-hackers@lists.postgresql.org>
Subject: AW: BUG #17448: In Windows 10, version 1703 and later, huge_pages
 doesn't work.
Thread-Topic: BUG #17448: In Windows 10, version 1703 and later, huge_pages
 doesn't work.
Thread-Index: AQHYQLLari2s00oie0yrcUkVcNdgtqzRF5eAgAAr+QCAAC3FgIAGApsAgAFhPgCAAC2tgIAABR2AgAAuZoCAAASEgIABhzwQgCbuaICAAcnTAIAAPCWg
Date: Wed, 27 Apr 2022 15:04:23 +0000
Message-ID: <9178d683d05d420a887369ffb38d8fbd@dental-vision.de>
References: <20220326082408.moh55zuecxjmewnm@jrouhaud>
 <CA+hUKGLwOSf-QwVtCcKx9xvugN2BSzEBBeD5DNyTXgcSRp5sTw@mail.gmail.com>
 <YkQMyhsP7xgLDDT/@paquier.xyz> <20220331045908.bm5edcacvymgwwv2@jrouhaud>
 <YkVbbZBiC4yxXPuc@paquier.xyz> <20220331080055.hjrrsrd4lxwlt7f5@jrouhaud>
 <20220331104659.ol6pqe7s3tpkymuk@jrouhaud>
 <20220331110309.ws25d6dl5yyzprye@jrouhaud>
 <a6859029835d4abdb6ba2970614905d1@dental-vision.de>
 <Ymd7C+QineDpi7Eb@jrouhaud> <Ymj7GHBfTnaN5kWW@paquier.xyz>
In-Reply-To: <Ymj7GHBfTnaN5kWW@paquier.xyz>
Accept-Language: de-DE, en-US
Content-Language: de-DE
Content-Type: text/plain; charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Archived-At: <https://www.postgresql.org/message-id/9178d683d05d420a887369ffb38d8fbd%40dental-vision.de>
Precedence: bulk


On Tue, Apr 26, 2022 at 12:54:35PM +0800, Julien Rouhaud wrote:
>> I searched a bit and apparently some people are using this function=20
>> directly opening some dll, which seems wrong.

> I was wondering about this whole business, and the manifest approach is a=
 *horrible* design for an API where the goal is to know if your run-time en=
vironment is greater than a given threshold.

Agreed for the use case at hand, where you want to use one core API Functio=
n or another depending on the OS Version.

One Blog from Microsoft, I remember, told that one reason for the change we=
re the increase of false installation error messages "Install Error - Your =
system does not meet the minimum supported operating system and service pac=
k level."
where the software in question was written for Windows XP and the user trie=
d to install it on, say, Windows 8.
That is just a Developer-Pilot error, where the Developers forgot to antici=
pate future OS Versions and instead of checking for Version at least, where=
 checking for Version equality of all at design time known Windows Version.
Since you can develop only against OS APIs known at design time, and Micros=
oft claims to be pretty good at maintaining backward compatible facades for=
 their APIs, there is some reason in that decision.
(To only see the Versions and APIs you told the OS with the manifest, you k=
new about at compile time).
The core Problem at hand is, that ms broke the promise of backward compatib=
ility, since the function in question is working differently, depending on =
windows version, although with the above reasoning we should get the exact =
same behavior on windows 10 as on windows 8.1 (as PostgreSql, per default, =
only claims to know about Windows 8.1 features).

That said, I can understand the design decision. Personally, I still don't =
like it a bit, since developers should be allowed to make some stupid mista=
kes.

>>> Another Idea on windows machines would be to use the commandline to=20
>>> execute ver in a separate Process and store the result in a file.
>>=20
>> That also seems hackish, I don't think that we want to rely on=20
>> something like that.

>Hmm.  That depends on the dependency set, I guess.  We do that on Linux at=
 some extent to for large pages in sysv_shmem.c.  Perhaps this could work f=
or Win10 if this avoids the extra loopholes with the >manifests.

I used the following hack to get the "real" Major and Minor Version of Wind=
ows - it's in C# (.Net) and needs to be adjusted (you can compile as x64 an=
d use a long-long as return value ) to return the Service Number too and tr=
anslated it into C.
I share it anyways, as it might help - please be kind, as it really is a li=
ttle hack.

Situation:=20
Main Application can't or is not willing to add a manifest file into its re=
sources.

Solution:
Start a small executable (which has a manifest file compiled into its resou=
rces), let it read the OS Version and code the Version into its return Code=
.

CInt32 is basically an integer redefinition, where one can access the lower=
 and higher Int16 separately.

The Main Programm eventually calls this (locate the executable, adjust the =
Process startup to be minimal, call the executable as separate process and =
interpret the return value as Version):
private static Version ReadModernOsVersionInternal()
{
    String codeBase =3D Assembly.GetExecutingAssembly().CodeBase;
    Uri uri =3D new Uri(codeBase);

    String localPath =3D uri.LocalPath;
    String pathDirectory =3D Path.GetDirectoryName(localPath);

    if (pathDirectory !=3D null)
    {
        String fullCombinePath =3D Path.Combine(pathDirectory, "Cf.Utilitie=
s.ReadModernOSVersion");

        ProcessStartInfo processInfo =3D new ProcessStartInfo
        {
            FileName =3D fullCombinePath,
            CreateNoWindow =3D true,
            UseShellExecute =3D false
        };

        Process process =3D new Process
        {
            StartInfo =3D processInfo
        };

        process.Start();

        if (process.WaitForExit(TimeSpan.FromSeconds(1).Milliseconds))
        {
            CInt32 versionInteger =3D process.ExitCode;
            return new Version(versionInteger.HighValue, versionInteger.Low=
Value);
        }
    }

    return new Version();
}


The small Version Check executable:

static Int32 Main(String[] args)
{
    return OsVersionErmittler.ErmittleOsVersion();
}

and

static class OsVersionErmittler
{
    /// <summary>
    /// Ermittelt die OsVersion und =FCbergibt diese als High und LowWord.
    /// </summary>
    /// <returns></returns>
    public static CInt32 ErmittleOsVersion()
    {
        OperatingSystem version =3D Environment.OSVersion;
        if (version.Platform =3D=3D PlatformID.Win32NT && version.Version >=
=3D new Version(6, 3))
        {
            String versionString =3D version.VersionString;
            return new CInt32((Int16) version.Version.Major, (Int16) versio=
n.Version.Minor);
        }
        return 0;
    }
}

The shortened manifest of the small executable:
<?xml version=3D"1.0" encoding=3D"utf-8"?>
<assembly manifestVersion=3D"1.0" xmlns=3D"urn:schemas-microsoft-com:asm.v1=
">
    <compatibility xmlns=3D"urn:schemas-microsoft-com:compatibility.v1">
    <application>
      <!-- Eine Liste der Windows-Versionen, unter denen diese Anwendung ge=
testet
           und f=FCr die sie entwickelt wurde. Wenn Sie die Auskommentierun=
g der entsprechenden Elemente aufheben,=20
           wird von Windows automatisch die kompatibelste Umgebung ausgew=
=E4hlt. -->

      <!-- Windows Vista -->
      <!--<supportedOS Id=3D"{e2011457-1546-43c5-a5fe-008deee3d3f0}" />-->

      <!-- Windows 7 -->
      <!--<supportedOS Id=3D"{35138b9a-5d96-4fbd-8e2d-a2440225f93a}" />-->

      <!-- Windows 8 -->
      <!--<supportedOS Id=3D"{4a2f28e3-53b9-4441-ba9c-d69d4a4a6e38}" />-->

      <!-- Windows 8.1 -->
      <supportedOS Id=3D"{1f676c76-80e1-4239-95bb-83d0f6d0da78}" />

      <!-- Windows 10 -->
      <supportedOS Id=3D"{8e0f7a12-bfb3-4fe8-b9a5-48fd50a15a9a}" />

    </application>
  </compatibility>

 </assembly>


I hope I'm not intrusive, otherwise, feel free to ignore this mail,
Wilm.