| Message ID | 20230403162823.30681-2-jgross@suse.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | xen: some CONFIG_DEBUG_INFO changes | expand |
On 03.04.2023 18:28, Juergen Gross wrote: > In order to support hypervisor analysis of crash dumps, xen-syms needs > to contain debug_info. It should be allowed to configure the hypervisor > to be built with CONFIG_DEBUG_INFO in non-debug builds without having > to enable EXPERT. > > Using a rather oldish gcc (7.5) it was verified that code generation > doesn't really differ between CONFIG_DEBUG_INFO on or off without > CONFIG_DEBUG being set (only observed differences were slightly > different symbol addresses, verified via "objdump -d", resulting from > the different config.gz in the binary). The old gcc version selection > was based on the assumption, that newer gcc won't regress in this > regard. > > So move CONFIG_DEBUG_INFO out of the section guarded by EXPERT. > > It should be mentioned that there have been reports that the linking > of the xen.efi might take considerably longer with CONFIG_DEBUG_INFO > selected when using newer binutils. Thinking of it: Because of the need to deal with older binutils, we already force --strip-debug as a linking option for xen.efi in certain cases. Perhaps we could make another (x86-only) Kconfig control which allows to force this mode even with recent binutils? If so, would you be willing to include this right here, or should I take care of this afterwards (or maybe even in parallel)? > --- a/xen/Kconfig.debug > +++ b/xen/Kconfig.debug > @@ -11,6 +11,13 @@ config DEBUG > > You probably want to say 'N' here. > > +config DEBUG_INFO > + bool "Compile Xen with debug info" > + default DEBUG > + help > + If you say Y here the resulting Xen will include debugging info > + resulting in a larger binary image. > + > if DEBUG || EXPERT Just to repeat my v1 comment (to which your response was "Fine with me"): The new placement isn't very helpful when considering some of the ways kconfig data is presented. At least for the non-graphical presentation it used to be the case that hierarchies were presented properly only when dependencies immediately followed their dependents (i.e. here: DEBUG is a dependent of everything inside the "if" above). Therefore I think rather than moving the block up you may better move it down past the "endif". Jan
On 05.04.23 15:14, Jan Beulich wrote: > On 03.04.2023 18:28, Juergen Gross wrote: >> In order to support hypervisor analysis of crash dumps, xen-syms needs >> to contain debug_info. It should be allowed to configure the hypervisor >> to be built with CONFIG_DEBUG_INFO in non-debug builds without having >> to enable EXPERT. >> >> Using a rather oldish gcc (7.5) it was verified that code generation >> doesn't really differ between CONFIG_DEBUG_INFO on or off without >> CONFIG_DEBUG being set (only observed differences were slightly >> different symbol addresses, verified via "objdump -d", resulting from >> the different config.gz in the binary). The old gcc version selection >> was based on the assumption, that newer gcc won't regress in this >> regard. >> >> So move CONFIG_DEBUG_INFO out of the section guarded by EXPERT. >> >> It should be mentioned that there have been reports that the linking >> of the xen.efi might take considerably longer with CONFIG_DEBUG_INFO >> selected when using newer binutils. > > Thinking of it: Because of the need to deal with older binutils, we > already force --strip-debug as a linking option for xen.efi in > certain cases. Perhaps we could make another (x86-only) Kconfig > control which allows to force this mode even with recent binutils? > If so, would you be willing to include this right here, or should I > take care of this afterwards (or maybe even in parallel)? I'm planning to do the EFI side in the next days, hoping that I can setup the test system. I'd include that additional config option in the probably needed patch(es) then (crash isn't happy with xen.efi anyway, so I'll need some kind of xen-syms.efi or whatever you want to call it). > >> --- a/xen/Kconfig.debug >> +++ b/xen/Kconfig.debug >> @@ -11,6 +11,13 @@ config DEBUG >> >> You probably want to say 'N' here. >> >> +config DEBUG_INFO >> + bool "Compile Xen with debug info" >> + default DEBUG >> + help >> + If you say Y here the resulting Xen will include debugging info >> + resulting in a larger binary image. >> + >> if DEBUG || EXPERT > > Just to repeat my v1 comment (to which your response was "Fine with me"): > > The new placement isn't very helpful when considering some of the ways > kconfig data is presented. At least for the non-graphical presentation > it used to be the case that hierarchies were presented properly only > when dependencies immediately followed their dependents (i.e. here: > DEBUG is a dependent of everything inside the "if" above). Therefore I > think rather than moving the block up you may better move it down past > the "endif". Oh, I seem to have missed that last paragraph when going through the thread. Will correct it. Juergen
diff --git a/xen/Kconfig.debug b/xen/Kconfig.debug index fad3050d4f..e0d773d347 100644 --- a/xen/Kconfig.debug +++ b/xen/Kconfig.debug @@ -11,6 +11,13 @@ config DEBUG You probably want to say 'N' here. +config DEBUG_INFO + bool "Compile Xen with debug info" + default DEBUG + help + If you say Y here the resulting Xen will include debugging info + resulting in a larger binary image. + if DEBUG || EXPERT config CRASH_DEBUG @@ -28,13 +35,6 @@ config GDBSX If you want to enable support for debugging guests from dom0 via gdbsx then say Y. -config DEBUG_INFO - bool "Compile Xen with debug info" - default y - ---help--- - If you say Y here the resulting Xen will include debugging info - resulting in a larger binary image. - config FRAME_POINTER bool "Compile Xen with frame pointers" default DEBUG
In order to support hypervisor analysis of crash dumps, xen-syms needs to contain debug_info. It should be allowed to configure the hypervisor to be built with CONFIG_DEBUG_INFO in non-debug builds without having to enable EXPERT. Using a rather oldish gcc (7.5) it was verified that code generation doesn't really differ between CONFIG_DEBUG_INFO on or off without CONFIG_DEBUG being set (only observed differences were slightly different symbol addresses, verified via "objdump -d", resulting from the different config.gz in the binary). The old gcc version selection was based on the assumption, that newer gcc won't regress in this regard. So move CONFIG_DEBUG_INFO out of the section guarded by EXPERT. It should be mentioned that there have been reports that the linking of the xen.efi might take considerably longer with CONFIG_DEBUG_INFO selected when using newer binutils. Signed-off-by: Juergen Gross <jgross@suse.com> --- V2: - expanded commit message (Jan Beulich) --- xen/Kconfig.debug | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)