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Diffstat (limited to 'gdb/doc/gdb.texinfo')
| -rw-r--r-- | gdb/doc/gdb.texinfo | 84 |
1 files changed, 81 insertions, 3 deletions
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index b251c8e..362e6e7 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -4090,6 +4090,56 @@ When @samp{on} @value{GDBN} will print additional messages when threads are created and deleted. @end table +@cindex thread local storage +@cindex @acronym{TLS} +For some debugging targets, @value{GDBN} has support for accessing +variables that reside in Thread Local Storage (@acronym{TLS}). +@acronym{TLS} variables are similar to global variables, except that +each thread has its own copy of the variable. While often used in +multi-threaded programs, @acronym{TLS} variables can also be used in +programs without threads. The C library variable @var{errno} is, +perhaps, the most prominent example of a @acronym{TLS} variable that +is frequently used in non-threaded programs. For targets where +@value{GDBN} does not have good @acronym{TLS} support, printing or +changing the value of @var{errno} might not be directly possible. + +@sc{gnu}/Linux and FreeBSD targets have support for accessing +@acronym{TLS} variables. On @sc{gnu}/Linux, the helper library, +@code{libthread_db}, is used to help resolve the addresses of +@acronym{TLS} variables. Some FreeBSD and some @sc{gnu}/Linux targets +also have @value{GDBN}-internal @acronym{TLS} resolution code. +@sc{gnu}/Linux targets will attempt to use the @acronym{TLS} address +lookup functionality provided by @code{libthread_db}, but will fall +back to using its internal @acronym{TLS} support when +@code{libthread_db} is not available. This can happen in +cross-debugging scenarios or when debugging programs that are linked +in such a way that @code{libthread_db} support is unavailable -- this +includes statically linked programs, linking against @acronym{GLIBC} +versions earlier than 2.34, but not with @code{libpthread}, and use of +other (non-@acronym{GLIBC}) C libraries. + +@table @code +@kindex maint set force-internal-tls-address-lookup +@kindex maint show force-internal-tls-address-lookup +@cindex internal @acronym{TLS} address lookup +@item maint set force-internal-tls-address-lookup +@itemx maint show force-internal-tls-address-lookup +Turns on or off forced use of @value{GDBN}-internal @acronym{TLS} +address lookup code. Use @code{on} to enable and @code{off} to +disable. The default for this setting is @code{off}. + +When disabled, @value{GDBN} will attempt to use a helper +@code{libthread_db} library if possible, but will fall back to use of +its own internal @acronym{TLS} address lookup mechanisms if necessary. + +When enabled, @value{GDBN} will only use @value{GDBN}'s internal +@acronym{TLS} address lookup mechanisms, if they exist. + +This command is only available for @sc{gnu}/Linux targets. Its +primary use is for testing -- certain tests in the @value{GDBN} test +suite use this command to force use of internal TLS address lookup. +@end table + @node Forks @section Debugging Forks @@ -7807,9 +7857,9 @@ previous instruction; otherwise, it will work in record mode, if the platform supports reverse execution, or stop if not. Currently, process record and replay is supported on ARM, Aarch64, -LoongArch, Moxie, PowerPC, PowerPC64, S/390, and x86 (i386/amd64) running -GNU/Linux. Process record and replay can be used both when native -debugging, and when remote debugging via @code{gdbserver}. +LoongArch, Moxie, PowerPC, PowerPC64, S/390, RISC-V and x86 (i386/amd64) +running GNU/Linux. Process record and replay can be used both when +native debugging, and when remote debugging via @code{gdbserver}. When recording an inferior, @value{GDBN} may print auxiliary information during stepping commands and commands displaying the execution history. @@ -13046,6 +13096,18 @@ variable which may be @samp{truecolor} or @samp{24bit}. Other color spaces are determined by the "Co" termcap which in turn depends on the @env{TERM} environment variable. +@vindex $_active_linker_namespaces@r{, convenience variable} +@item $_active_linker_namespaces +Number of active linkage namespaces in the inferior. In systems with no +support for linkage namespaces, this variable will always be set to @samp{1}. + +@vindex $_current_linker_namespace@r{, convenience variable} +@item $_current_linker_namespace +The namespace which contains the current location in the inferior. This +returns GDB's internal identifier for namespaces, which is @samp{[[@var{n}]]} +where @var{n} is a zero-based namespace number. In systems with no support +for linkage namespaces, this variable will always be set to @samp{[[0]]}. + @end table @node Convenience Funs @@ -22212,6 +22274,22 @@ less useful than setting a catchpoint, because it does not allow for conditions or commands as a catchpoint does. @table @code +@kindex info linker-namespaces +@item info linker-namespaces +@item info linker-namespaces @code{[[@var{n}]]} + +With no argument, print the number of linker namespaces which are +currently active --- that is, namespaces that have libraries loaded +into them. Then, it prints the number of libraries loaded into each +namespace, and all the libraries loaded into them, in the same way +as @code{info sharedlibrary}. + +If an argument @code{[[@var{n}]]} is provided, only prints the +library count and the libraried for the provided namespace @var{n}. +The surrounding square brackets are optional. +@end table + +@table @code @item set stop-on-solib-events @kindex set stop-on-solib-events This command controls whether @value{GDBN} should give you control |