MTD 248-645A Manual de usuario descargar pdf (Pagina 214)

Linux From Scratch - Version 7.0

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6.62. About Debugging Symbols

Most programs and libraries are, by default, compiled with debugging symbols included (with gcc's -g option).

This means that when debugging a program or library that was compiled with debugging information included, the

debugger can provide not only memory addresses, but also the names of the routines and variables.

However, the inclusion of these debugging symbols enlarges a program or library significantly. The following is an

example of the amount of space these symbols occupy:

• A bash binary with debugging symbols: 1200 KB

• A bash binary without debugging symbols: 480 KB

• Glibc and GCC files (/lib and /usr/lib) with debugging symbols: 87 MB

• Glibc and GCC files without debugging symbols: 16 MB

Sizes may vary depending on which compiler and C library were used, but when comparing programs with and

without debugging symbols, the difference will usually be a factor between two and five.

Because most users will never use a debugger on their system software, a lot of disk space can be regained by removing

these symbols. The next section shows how to strip all debugging symbols from the programs and libraries.

6.63. Stripping Again

If the intended user is not a programmer and does not plan to do any debugging on the system software, the system

size can be decreased by about 90 MB by removing the debugging symbols from binaries and libraries. This causes

no inconvenience other than not being able to debug the software fully anymore.

Most people who use the command mentioned below do not experience any difficulties. However, it is easy to make

a typo and render the new system unusable, so before running the strip command, it is a good idea to make a backup

of the LFS system in its current state.

Before performing the stripping, take special care to ensure that none of the binaries that are about to be stripped

are running. If unsure whether the user entered chroot with the command given in Section 6.4, “Entering the Chroot

Environment,” first exit from chroot:

logout

Then reenter it with:

chroot $LFS /tools/bin/env -i \

HOME=/root TERM=$TERM PS1='\u:\w\$ ' \

PATH=/bin:/usr/bin:/sbin:/usr/sbin \

/tools/bin/bash --login

Now the binaries and libraries can be safely stripped:

/tools/bin/find /{,usr/}{bin,lib,sbin} -type f \

-exec /tools/bin/strip --strip-debug '{}' ';'

A large number of files will be reported as having their file format not recognized. These warnings can be safely

ignored. These warnings indicate that those files are scripts instead of binaries.

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MTD 248-645A Manual de usuario Pagina 214