Re: [PATCH] Implemented sysconf for Arm

The 07/29/2020 17:43, Corinna Vinschen via Newlib wrote:
> And again adding Richard.
> 
> Richard, is nobody from ARM looking into this stuff, at least once in a
> while?

i don't know what's the best way to do
link-time or run-time configuration of
newlib internals.

it seems to me that malloc allocation
granule does not have to use page size
as defined in the arm architecture nor
page size as defined in posix nor
page size as defined in the elf abi.

so ideally there would be a hook with
different name that users can link-time
override. (so there is no danger of
something trying to use _SC_PAGESIZE
or sysconf in general for something else
that conflicts with the malloc usage)

but if currently sysconf is only used by
malloc in newlib then i guess the patch
works (i'd add a comment though that it
is the malloc block size and not a
property of the memory system).


> 
> 
> Corinna
> 
> 
> On Jul 29 15:26, Torbjorn SVENSSON via Newlib wrote:
> > Ping3
> > 
> > -----Original Message-----
> > From: Torbjorn SVENSSON 
> > Sent: den 19 maj 2020 18:17
> > To: [email protected]
> > Cc: Niklas DAHLQUIST <[email protected]>
> > Subject: RE: [PATCH] Implemented sysconf for Arm
> > 
> > Ping2!
> > 
> > If it's not clear to the reviewer, the use-case that we want to fulfill here is to be able to override the page size for the malloc() call for the project and not require a new build of newlib.
> > With this approach, simply re-implementing the function sysconf(int) in the application to return the appropriate page size for the application and have the linker will select the local implementation over the newlib provided one is enough to reserve a smaller memory block for malloc.
> > 
> > I also need assistance to push the patch since I've not got commit access.
> > 
> > Thanks.
> > 
> > Torbjörn
> > 
> > -----Original Message-----
> > From: Torbjorn SVENSSON 
> > Sent: den 7 maj 2020 10:29
> > To: Newlib <[email protected]>
> > Cc: Niklas DAHLQUIST <[email protected]>
> > Subject: RE: [PATCH] Implemented sysconf for Arm
> > 
> > Ping
> > 
> > -----Original Message-----
> > From: Newlib <[email protected]> On Behalf Of Torbjorn SVENSSON via Newlib
> > Sent: den 27 april 2020 17:31
> > To: [email protected]
> > Cc: Niklas DAHLQUIST <[email protected]>
> > Subject: [PATCH] Implemented sysconf for Arm
> > 
> > The default implementation can be overridden outside newlib to allow a
> > different page size to improve malloc on devices with a small footprint
> > without needing to rebuild newlib.
> > 
> > Signed-off-by: Torbjörn SVENSSON <[email protected]>
> > Signed-off-by: Niklas DAHLQUIST <[email protected]>
> > ---
> >  newlib/libc/stdlib/mallocr.c    |  2 +-
> >  newlib/libc/sys/arm/Makefile.am |  2 +-
> >  newlib/libc/sys/arm/Makefile.in | 12 ++++++++++--
> >  newlib/libc/sys/arm/sysconf.c   | 20 ++++++++++++++++++++
> >  4 files changed, 32 insertions(+), 4 deletions(-)
> >  create mode 100644 newlib/libc/sys/arm/sysconf.c
> > 
> > diff --git a/newlib/libc/stdlib/mallocr.c b/newlib/libc/stdlib/mallocr.c
> > index 26d1c89cc..28d278f51 100644
> > --- a/newlib/libc/stdlib/mallocr.c
> > +++ b/newlib/libc/stdlib/mallocr.c
> > @@ -316,7 +316,7 @@ extern "C" {
> >  # undef WIN32
> >  #endif
> >  
> > -#ifndef _WIN32
> > +#if !defined(_WIN32) && !defined(__ARM_EABI__)
> >  #ifdef SMALL_MEMORY
> >  #define malloc_getpagesize (128)
> >  #else
> > diff --git a/newlib/libc/sys/arm/Makefile.am b/newlib/libc/sys/arm/Makefile.am
> > index 711872de3..9111f3647 100644
> > --- a/newlib/libc/sys/arm/Makefile.am
> > +++ b/newlib/libc/sys/arm/Makefile.am
> > @@ -14,7 +14,7 @@ else
> >  extra_objs =
> >  endif
> >  
> > -lib_a_SOURCES = access.c aeabi_atexit.c
> > +lib_a_SOURCES = access.c aeabi_atexit.c sysconf.c
> >  lib_a_LIBADD = $(extra_objs)
> >  EXTRA_lib_a_SOURCES = trap.S syscalls.c libcfunc.c
> >  lib_a_DEPENDENCIES = $(extra_objs)
> > diff --git a/newlib/libc/sys/arm/Makefile.in b/newlib/libc/sys/arm/Makefile.in
> > index c01e4e2ed..67fb695f5 100644
> > --- a/newlib/libc/sys/arm/Makefile.in
> > +++ b/newlib/libc/sys/arm/Makefile.in
> > @@ -70,7 +70,8 @@ ARFLAGS = cru
> >  lib_a_AR = $(AR) $(ARFLAGS)
> >  @MAY_SUPPLY_SYSCALLS_TRUE@am__DEPENDENCIES_1 = $(lpfx)libcfunc.o \
> >  @MAY_SUPPLY_SYSCALLS_TRUE@	$(lpfx)trap.o $(lpfx)syscalls.o
> > -am_lib_a_OBJECTS = lib_a-access.$(OBJEXT) lib_a-aeabi_atexit.$(OBJEXT)
> > +am_lib_a_OBJECTS = lib_a-access.$(OBJEXT) lib_a-aeabi_atexit.$(OBJEXT) \
> > +	lib_a-sysconf.$(OBJEXT)
> >  lib_a_OBJECTS = $(am_lib_a_OBJECTS)
> >  DEFAULT_INCLUDES = -I.@am__isrc@
> >  depcomp =
> > @@ -183,6 +184,7 @@ pdfdir = @pdfdir@
> >  prefix = @prefix@
> >  program_transform_name = @program_transform_name@
> >  psdir = @psdir@
> > +runstatedir = @runstatedir@
> >  sbindir = @sbindir@
> >  sharedstatedir = @sharedstatedir@
> >  srcdir = @srcdir@
> > @@ -198,7 +200,7 @@ AM_CCASFLAGS = $(INCLUDES)
> >  noinst_LIBRARIES = lib.a
> >  @MAY_SUPPLY_SYSCALLS_FALSE@extra_objs = 
> >  @MAY_SUPPLY_SYSCALLS_TRUE@extra_objs = $(lpfx)libcfunc.o $(lpfx)trap.o $(lpfx)syscalls.o
> > -lib_a_SOURCES = access.c aeabi_atexit.c
> > +lib_a_SOURCES = access.c aeabi_atexit.c sysconf.c
> >  lib_a_LIBADD = $(extra_objs)
> >  EXTRA_lib_a_SOURCES = trap.S syscalls.c libcfunc.c
> >  lib_a_DEPENDENCIES = $(extra_objs)
> > @@ -288,6 +290,12 @@ lib_a-aeabi_atexit.o: aeabi_atexit.c
> >  lib_a-aeabi_atexit.obj: aeabi_atexit.c
> >  	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-aeabi_atexit.obj `if test -f 'aeabi_atexit.c'; then $(CYGPATH_W) 'aeabi_atexit.c'; else $(CYGPATH_W) '$(srcdir)/aeabi_atexit.c'; fi`
> >  
> > +lib_a-sysconf.o: sysconf.c
> > +	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-sysconf.o `test -f 'sysconf.c' || echo '$(srcdir)/'`sysconf.c
> > +
> > +lib_a-sysconf.obj: sysconf.c
> > +	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-sysconf.obj `if test -f 'sysconf.c'; then $(CYGPATH_W) 'sysconf.c'; else $(CYGPATH_W) '$(srcdir)/sysconf.c'; fi`
> > +
> >  lib_a-syscalls.o: syscalls.c
> >  	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-syscalls.o `test -f 'syscalls.c' || echo '$(srcdir)/'`syscalls.c
> >  
> > diff --git a/newlib/libc/sys/arm/sysconf.c b/newlib/libc/sys/arm/sysconf.c
> > new file mode 100644
> > index 000000000..86a324fa4
> > --- /dev/null
> > +++ b/newlib/libc/sys/arm/sysconf.c
> > @@ -0,0 +1,20 @@
> > +/* libc/sys/arm/sysconf.c - The sysconf function */
> > +
> > +/* Copyright 2020, STMicroelectronics */
> > +
> > +#include <unistd.h>
> > +#include <errno.h>
> > +
> > +long sysconf(int name)
> > +{
> > +  switch (name)
> > +  {
> > +  case _SC_PAGESIZE:
> > +    return 4096;
> > +
> > +  default:
> > +    errno = EINVAL;
> > +    return -1;
> > +  }
> > +  return -1; /* Can't get here */
> > +}
> > -- 
> > 2.18.0
> 
> -- 
> Corinna Vinschen
> Cygwin Maintainer
> Red Hat
> 

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