| Message ID | 20201215133019.14411-1-alx.manpages@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | [v6] cacheflush.2: Document __builtin___clear_cache() as a more portable alternative | expand |
Ping On 12/15/20 2:30 PM, Alejandro Colomar wrote: > Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com> > Cc: Martin Sebor <msebor@redhat.com> > Cc: Dave Martin <Dave.Martin@arm.com> > --- > > v6: > - GCC has always exposed 'void *', as Martin Sebor noted. > It's Clang (and maybe others) that (following GCC's docs) > exposed 'char *'. > > man2/cacheflush.2 | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/man2/cacheflush.2 b/man2/cacheflush.2 > index aba625721..7a2eed506 100644 > --- a/man2/cacheflush.2 > +++ b/man2/cacheflush.2 > @@ -86,6 +86,30 @@ On Linux, this call first appeared on the MIPS architecture, > but nowadays, Linux provides a > .BR cacheflush () > system call on some other architectures, but with different arguments. > +.SH NOTES > +Unless you need the finer grained control that this system call provides, > +you probably want to use the GCC built-in function > +.BR __builtin___clear_cache (), > +which provides a portable interface > +across platforms supported by GCC and compatible compilers: > +.PP > +.in +4n > +.EX > +.BI "void __builtin___clear_cache(void *" begin ", void *" end ); > +.EE > +.in > +.PP > +On platforms that don't require instruction cache flushes, > +.BR __builtin___clear_cache () > +has no effect. > +.PP > +.IR Note : > +On some GCC-compatible compilers, > +the prototype for this built-in function uses > +.I char * > +instead of > +.I void * > +for the parameters. > .SH BUGS > Linux kernels older than version 2.6.11 ignore the > .I addr >
On 12/15/20 2:30 PM, Alejandro Colomar wrote: > Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de> > Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com> > Cc: Martin Sebor <msebor@redhat.com> > Cc: Dave Martin <Dave.Martin@arm.com> > --- > > v6: > - GCC has always exposed 'void *', as Martin Sebor noted. > It's Clang (and maybe others) that (following GCC's docs) > exposed 'char *'. Thanks, Alex. Patch applied. Cheers, Michael > man2/cacheflush.2 | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/man2/cacheflush.2 b/man2/cacheflush.2 > index aba625721..7a2eed506 100644 > --- a/man2/cacheflush.2 > +++ b/man2/cacheflush.2 > @@ -86,6 +86,30 @@ On Linux, this call first appeared on the MIPS architecture, > but nowadays, Linux provides a > .BR cacheflush () > system call on some other architectures, but with different arguments. > +.SH NOTES > +Unless you need the finer grained control that this system call provides, > +you probably want to use the GCC built-in function > +.BR __builtin___clear_cache (), > +which provides a portable interface > +across platforms supported by GCC and compatible compilers: > +.PP > +.in +4n > +.EX > +.BI "void __builtin___clear_cache(void *" begin ", void *" end ); > +.EE > +.in > +.PP > +On platforms that don't require instruction cache flushes, > +.BR __builtin___clear_cache () > +has no effect. > +.PP > +.IR Note : > +On some GCC-compatible compilers, > +the prototype for this built-in function uses > +.I char * > +instead of > +.I void * > +for the parameters. > .SH BUGS > Linux kernels older than version 2.6.11 ignore the > .I addr >
diff --git a/man2/cacheflush.2 b/man2/cacheflush.2 index aba625721..7a2eed506 100644 --- a/man2/cacheflush.2 +++ b/man2/cacheflush.2 @@ -86,6 +86,30 @@ On Linux, this call first appeared on the MIPS architecture, but nowadays, Linux provides a .BR cacheflush () system call on some other architectures, but with different arguments. +.SH NOTES +Unless you need the finer grained control that this system call provides, +you probably want to use the GCC built-in function +.BR __builtin___clear_cache (), +which provides a portable interface +across platforms supported by GCC and compatible compilers: +.PP +.in +4n +.EX +.BI "void __builtin___clear_cache(void *" begin ", void *" end ); +.EE +.in +.PP +On platforms that don't require instruction cache flushes, +.BR __builtin___clear_cache () +has no effect. +.PP +.IR Note : +On some GCC-compatible compilers, +the prototype for this built-in function uses +.I char * +instead of +.I void * +for the parameters. .SH BUGS Linux kernels older than version 2.6.11 ignore the .I addr
Reported-by: Heinrich Schuchardt <xypron.glpk@gmx.de> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com> Cc: Martin Sebor <msebor@redhat.com> Cc: Dave Martin <Dave.Martin@arm.com> --- v6: - GCC has always exposed 'void *', as Martin Sebor noted. It's Clang (and maybe others) that (following GCC's docs) exposed 'char *'. man2/cacheflush.2 | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+)