[PATCH 1/6] i386/pc386: configurable size of descriptor tables

Gedare Bloom gedare at rtems.org
Wed Nov 12 15:20:21 UTC 2014


On Wed, Nov 12, 2014 at 10:07 AM, Jan Dolezal <dolezj21 at fel.cvut.cz> wrote:
> ---
>  c/src/lib/libbsp/i386/pc386/Makefile.am           |  1 +
>  c/src/lib/libbsp/i386/pc386/configure.ac          |  5 +++++
>  c/src/lib/libbsp/i386/pc386/include/bsp.h         |  6 ++----
>  c/src/lib/libbsp/i386/pc386/include/bsptblsizes.h | 25 ++++++++++++++++++++++
>  c/src/lib/libbsp/i386/pc386/preinstall.am         |  4 ++++
>  c/src/lib/libbsp/i386/pc386/startup/ldsegs.S      | 26 +++++++++++++++++++----
>  6 files changed, 59 insertions(+), 8 deletions(-)
>  create mode 100644 c/src/lib/libbsp/i386/pc386/include/bsptblsizes.h
>
> diff --git a/c/src/lib/libbsp/i386/pc386/Makefile.am b/c/src/lib/libbsp/i386/pc386/Makefile.am
> index 22ba5e9..9c901df 100644
> --- a/c/src/lib/libbsp/i386/pc386/Makefile.am
> +++ b/c/src/lib/libbsp/i386/pc386/Makefile.am
> @@ -15,6 +15,7 @@ include_bspdir = $(includedir)/bsp
>  dist_project_lib_DATA = bsp_specs
>
>  include_HEADERS = include/bsp.h
> +include_HEADERS += include/bsptblsizes.h
This header should probably be nested under bsp at least.

>  include_HEADERS += include/tm27.h
>
>  nodist_include_HEADERS = include/bspopts.h
> diff --git a/c/src/lib/libbsp/i386/pc386/configure.ac b/c/src/lib/libbsp/i386/pc386/configure.ac
> index 1125c7c..ecec056 100644
> --- a/c/src/lib/libbsp/i386/pc386/configure.ac
> +++ b/c/src/lib/libbsp/i386/pc386/configure.ac
> @@ -82,6 +82,11 @@ RTEMS_BSPOPTS_HELP([USE_CIRRUS_GD5446],
>   NOTE: This has only been tested on Qemu.])
>  AM_CONDITIONAL(USE_CIRRUS_GD5446,test "$USE_CIRRUS_GD5446" = "1")
>
> +RTEMS_BSPOPTS_SET([NUM_APP_DRV_GDT_DESCRIPTORS],[*],[0])
> +RTEMS_BSPOPTS_HELP([NUM_APP_DRV_GDT_DESCRIPTORS],
> +[Defines how many descriptors in GDT may be allocated for application or
> + driver usage.])
> +
>  if test X${CLOCK_DRIVER_USE_TSC} = X1 -a X${CLOCK_DRIVER_USE_8254} = X1 ; then
>    AC_MSG_ERROR([pc386 both TSC and 8254 specified for clock driver])
>  fi
> diff --git a/c/src/lib/libbsp/i386/pc386/include/bsp.h b/c/src/lib/libbsp/i386/pc386/include/bsp.h
> index 21aa054..3425a6d 100644
> --- a/c/src/lib/libbsp/i386/pc386/include/bsp.h
> +++ b/c/src/lib/libbsp/i386/pc386/include/bsp.h
> @@ -51,6 +51,7 @@
>
>  #include <bspopts.h>
>  #include <bsp/default-initial-extension.h>
> +#include <bsptblsizes.h>
>
>  #include <rtems.h>
>  #include <rtems/iosupp.h>
> @@ -166,11 +167,8 @@ extern int rtems_3c509_driver_attach(struct rtems_bsdnet_ifconfig *config);
>  /*-------------------------------------------------------------------------+
>  | External Variables.
>  +--------------------------------------------------------------------------*/
> -#define IDT_SIZE 256
> -#define GDT_SIZE 3
> -
Why not just update these #defines with the new  ones you have in bsptblsizes.h?

>  extern interrupt_gate_descriptor Interrupt_descriptor_table[IDT_SIZE];
> -extern segment_descriptors Global_descriptor_table   [GDT_SIZE];
> +extern segment_descriptors _Global_descriptor_table   [GDT_SIZE];
>
>  /*-------------------------------------------------------------------------+
>  | Function Prototypes.
> diff --git a/c/src/lib/libbsp/i386/pc386/include/bsptblsizes.h b/c/src/lib/libbsp/i386/pc386/include/bsptblsizes.h
> new file mode 100644
> index 0000000..ef51ae7
> --- /dev/null
> +++ b/c/src/lib/libbsp/i386/pc386/include/bsptblsizes.h
> @@ -0,0 +1,25 @@
> +/**
> + * @file
> + *
> + * @ingroup i386_pc386
> + *
> + * @brief Sizes of Global and Interrupt descriptor tables.
> + */
> +
> +/*
> + * Definitions related to the PC386 BSP.
> + * This header file is also used in assembler modules.
> + *
> + * Copyright (C) 2014  Jan Doležal (dolezj21 at fel.cvut.cz)
> + *                     CTU in Prague.
> + *
> + *  The license and distribution terms for this file may be
> + *  found in the file LICENSE in this distribution or at
> + *  http://www.rtems.org/license/LICENSE.
> + */
> +
> +#include <bspopts.h>
> +
> +#define IDT_SIZE (256)
> +#define GDT_SIZE (3 + NUM_APP_DRV_GDT_DESCRIPTORS)
> +
> diff --git a/c/src/lib/libbsp/i386/pc386/preinstall.am b/c/src/lib/libbsp/i386/pc386/preinstall.am
> index 182f564..aff01dc 100644
> --- a/c/src/lib/libbsp/i386/pc386/preinstall.am
> +++ b/c/src/lib/libbsp/i386/pc386/preinstall.am
> @@ -41,6 +41,10 @@ $(PROJECT_INCLUDE)/bsp.h: include/bsp.h $(PROJECT_INCLUDE)/$(dirstamp)
>         $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/bsp.h
>  PREINSTALL_FILES += $(PROJECT_INCLUDE)/bsp.h
>
> +$(PROJECT_INCLUDE)/bsptblsizes.h: include/bsptblsizes.h $(PROJECT_INCLUDE)/$(dirstamp)
> +       $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/bsptblsizes.h
> +PREINSTALL_FILES += $(PROJECT_INCLUDE)/bsptblsizes.h
> +
>  $(PROJECT_INCLUDE)/tm27.h: include/tm27.h $(PROJECT_INCLUDE)/$(dirstamp)
>         $(INSTALL_DATA) $< $(PROJECT_INCLUDE)/tm27.h
>  PREINSTALL_FILES += $(PROJECT_INCLUDE)/tm27.h
> diff --git a/c/src/lib/libbsp/i386/pc386/startup/ldsegs.S b/c/src/lib/libbsp/i386/pc386/startup/ldsegs.S
> index 495d68a..8f2220d 100644
> --- a/c/src/lib/libbsp/i386/pc386/startup/ldsegs.S
> +++ b/c/src/lib/libbsp/i386/pc386/startup/ldsegs.S
> @@ -34,6 +34,15 @@
>  +--------------------------------------------------------------------------*/
>
>  #include <rtems/asm.h>
> +#include <bsptblsizes.h> /* contains sizes of GDT and IDT */
> +
> +#ifndef GDT_SIZE
> +#define GDT_SIZE (3)
> +#endif
> +
> +#ifndef IDT_SIZE
> +#define IDT_SIZE (256)
> +#endif
>
Adding ifndef here is redundant since they are unconditionally defined
in bsptblsizes.h

>  /*----------------------------------------------------------------------------+
>  | CODE section
> @@ -167,6 +176,9 @@ next_step:
>  /*---------------------------------------------------------------------------+
>  | GDT itself
>  +--------------------------------------------------------------------------*/
> +#if GDT_SIZE < 3
> +#error "GDT_SIZE must be at least 3"
> +#endif
>
Is there a way to use assert() type function in assembly or
preprocessor code? I'm just curious. This #if and #error is a good
thing to do at least, and I'm glad to see that you have it!

>  BEGIN_DATA
>         .p2align 4
> @@ -186,11 +198,17 @@ SYM (_Global_descriptor_table):
>         .word 0xffff, 0
>         .byte 0, 0x92, 0xcf, 0
>
> +        /* allocated space for user segments */
> +        .rept (GDT_SIZE - 3)
> +        .word 0,0,0,0
> +        .endr
> +
>  /*---------------------------------------------------------------------------+
>  | Descriptor of GDT
>  +--------------------------------------------------------------------------*/
> -SYM (gdtdesc):
> -       .word (3*8 - 1)
> +        PUBLIC(gdtdesc)
> +SYM(gdtdesc):
> +       .word (GDT_SIZE*8 - 1)
>         .long SYM (_Global_descriptor_table)
>
>  /*---------------------------------------------------------------------------+
> @@ -200,7 +218,7 @@ SYM (gdtdesc):
>
>         PUBLIC(Interrupt_descriptor_table)
>  SYM(Interrupt_descriptor_table):
> -       .rept 256
> +       .rept IDT_SIZE
>         .word 0,0,0,0
>         .endr
>
> @@ -211,7 +229,7 @@ SYM(Interrupt_descriptor_table):
>         .p2align 4
>         PUBLIC(IDT_Descriptor)
>  SYM(IDT_Descriptor):
> -       .word  (256*8 - 1)
> +       .word  (IDT_SIZE*8 - 1)
>         .long  SYM (Interrupt_descriptor_table)
>
>  END_DATA
> --
> 1.9.1
>
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