Changeset 850536a

Timestamp:

02/01/2024 09:05:49 AM (4 months ago)

Author:

Xi Ruoyao <xry111@…>

Branches:

xry111/update-glibc

Children:

10a450c

Parents:

d3b0a08

Message:

Add info about how to upgrade Glibc safely

Location:

chapter08

Files:

• glibc.xml (modified) (1 diff)
• pkgmgt.xml (modified) (1 diff)

chapter08/glibc.xml

@@ -201 +201 @@
 
 <screen><userinput remap="install">sed '/test-installation/s@$(PERL)@echo not running@' -i ../Makefile</userinput></screen>
+
+    <important>
+      <para>
+        If upgrading Glibc to a new minor version (for example, from
+        Glibc-2.36 to Glibc-&glibc-version;), you need to take some extra
+        caution to avoid breaking the system:
+      </para>
+
+      <itemizedlist>
+        <listitem>
+          <!-- There are two reasons we don't support this:
+               1. Upgrading on a system with separate /lib and /usr/lib is
+                  tricky.
+               2. With Glibc prior to 2.34 libc.so.6 etc. are symlinks to
+                  libc-2.33.so etc., again causing the upgradation tricky.
+                  The Glibc NEWS file explicit states they no longer use
+                  symlinks for the ABI names to avoid upgradation
+                  issues.  -->
+          <para>
+            Upgrading Glibc on a LFS system prior to 11.0 (exclusive) is
+            not supported.  Rebuild LFS if you are running such an old LFS
+            system but you need a newer Glibc.
+          </para>
+        </listitem>
+
+        <!-- https://sourceware.org/pipermail/libc-alpha/2024-January/154095.html -->
+        <listitem>
+          <para>
+            If upgrading on a LFS system prior to 12.0 (exclusive), install
+            <application>Libxcrypt</application> following
+            <xref role='.' linkend='ch-system-libxcrypt'/>  In addition to
+            a normal <application>Libxcrypt</application> installation,
+            <emphasis role='bold'>you MUST follow the note in Libxcrypt
+            section to install
+            <filename class='libraryfile'>libcrypt.so.1*</filename>
+            (overwritting
+            <filename class='libraryfile'>libcrypt.so.1</filename> from the
+            prior Glibc installation)</emphasis>.
+          </para>
+        </listitem>
+
+        <!-- Otherwise messages complaining "nscd disabled building Glibc"
+             will show up running things like sudo.  -->
+        <listitem revision='systemd'>
+          <para>
+            If upgrading on a LFS system based on Systemd prior to 12.1
+            (exclusive), disable and stop <command>nscd</command>:
+          </para>
+
+          <screen role='nodump'><userinput>systemctl disable --now nscd</userinput></screen>
+        </listitem>
+
+        <!-- This is to ensure we don't start a process at the time point
+             where some Glibc shared libraries are updated but the others
+             are not.  Such mismatches can cause programs crash on startup,
+             esp. a mismatch between ld-linux-x86-64.so.2 and
+             libc.so.6.  Note that a crash in the installation process
+             will leave the system in a state with the mismatch forever,
+             unrecoverable without the help of another distro.  -->
+        <listitem>
+          <para>
+            Perform a <envar>DESTDIR</envar> installation and upgrade
+            the Glibc shared libraries on the system using one single
+            <command>install</command> command:
+          </para>
+
+          <screen role='nodump'><userinput>make DESTDIR=$PWD/dest install
+install -vm755 dest/usr/lib/*.so.* /usr/lib</userinput></screen>
+        </listitem>
+      </itemizedlist>
+
+      <para>
+        It's imperative to strictly follow these steps above unless you
+        completely understand what you are doing.
+        <emphasis role='bold'>Any unproved deviation may render the system
+        completely unusable.  YOU ARE WARNED.</emphasis>
+      </para>
+
+      <para>
+        Then continue to follow the instructions on this page.  Once they
+        are finished, reboot the system immediately.
+      </para>
+    </important>
 
     <para>Install the package:</para>

chapter08/pkgmgt.xml

@@ -64 +64 @@
       <listitem>
         <para>If Glibc needs to be upgraded to a newer
-        version, (e.g.,  from Glibc-2.31 to Glibc-2.32), it is safer to
-        rebuild LFS.  Though you <emphasis>may</emphasis> be able to rebuild
-        all the packages in their dependency order, we do not recommend
-        it.  </para>
-      </listitem>
-
-      <listitem>
-        <para>Reinstalling the same version of Glibc (&glibc-version; for
-        this release of LFS) with patches should be safe when these patches
-        do not change ABI and API.  When a security vulnerability is found
-        in Glibc, we often need to apply such a patch to fix the
-        vulnerability and reinstall Glibc.  Consult
-        <ulink url='&lfs-root;lfs/advisories/'>LFS security
-        advisories</ulink> if you are alerted for a published Glibc security
-        vulnerability but unsure about the action to take.</para>
+        version, (e.g.,  from Glibc-2.36 to Glibc-&glibc-version;),
+        some extra steps are needed to avoid breaking the system.
+        Read <xref linkend='ch-system-glibc'/> for details.</para>
       </listitem>