gint/fx9860g.ld
Lephe 8148d89c88
core: backport TLB handling to fx9860g, fix return-to-menu (UNSTABLE)
This change ports the TLB management system to fx9860g through %003.
This raises the size limit for add-ins to about 500k.

Because SH3 fx9860g does not have ILRAM, the GMAPPED attribute has been
made to generate content to a .gint.mapped section which is sent to the
P1 RAM section historically dubbed "real ram" in which gint's data and
VBR are installed. (Now that I think about it, gint's data should try to
go to normal RAM instead to reduce pressure on this invasion.)

Return-to-menu was also fixed on both platforms by narrowing down the
need for code to remain mapped to the chance of running it with
interrupts disabled. The natural distribution of GMAPPED under this
criterion showed that _gint_setvbr had been left under TLB control;
moving it to the proper RAM area fixed gint switches.

Finally, an omission in the bound checks for mappable TEA addresses (TEA
>= 0x00300000) prevented the appearance of a non-interactible System
ERROR popup when some unmapped addresses are accessed.

This version still does not enable interrupts in timer callbacks,
exposing any application to a crash if a timer underflows while its
callback is not mapped. It is not suitable for any stable application!
2020-06-15 20:55:18 +02:00

255 lines
5.9 KiB
Text

/*
Linker script for the fx9860g platform. Most of the symbols defined
here are used in the initialization routine in core/start.c; others are
used in core/setup.c.
*/
/* fx9860g may mean SH3 or SH4 and we want full compatibility */
OUTPUT_ARCH(sh3)
/* ELF offers a lot of symbol/section/relocation insights */
OUTPUT_FORMAT(elf32-sh)
/* Located in core/start.c */
ENTRY(_start)
MEMORY
{
/* Userspace mapping of the add-in (G1A header takes 0x200 bytes) */
rom (rx): o = 0x00300200, l = 500k
/* This is mapped to RAM; 8k on SH3, apparently 32k on SH4 */
ram (rw): o = 0x08100000, l = 8k
/* gint's VBR space, mentioned here for completeness */
vbr (rwx): o = 0x8800e000, l = 5k
/* Some RAM region from P1 area; gint's data will reside here */
rram (rwx): o = 0x8800f400, l = 3k
/* On-chip IL memory */
ilram (rwx): o = 0xe5200000, l = 4k
/* On-chip X and Y memory */
xram (rwx): o = 0xe5007000, l = 8k
yram (rwx): o = 0xe5017000, l = 8k
}
SECTIONS
{
/*
** ROM sections
*/
/* First address to be mapped to ROM (including G1A header) */
_brom = 0x00300000;
/* Size of ROM mappings */
_srom = 0x200
+ SIZEOF(.text) + SIZEOF(.rodata)
+ SIZEOF(.gint.drivers) + SIZEOF(.gint.blocks);
/* Machine code going to ROM:
- Initialization sections (.pretext.entry and .pretext)
- Compiler-provided constructors (.ctors) and destructors (.dtors)
- All text from .text and .text.* (including user code)
- Code sections from fxlib, named "C" and "P" */
.pretext : {
*(.pretext.entry)
*(.pretext)
_btors = . ;
*(.ctors .ctors.*)
_mtors = . ;
*(.dtors .dtors.*)
_etors = . ;
} > rom
.text : {
_gint_exch_start = . ;
*(.gint.exch)
_gint_exch_size = ABSOLUTE(. - _gint_exch_start);
_gint_tlbh_start = . ;
*(.gint.tlbh)
_gint_tlbh_size = ABSOLUTE(. - _gint_tlbh_start);
*(.text .text.*)
*(C P)
} > rom
/* Interrupt handlers going to ROM:
- gint's interrupt handler blocks (.gint.blocks)
Although gint's blocks end up in VBR space, they are selected and
installed on-the-fly by the library and the drivers, so we can't
just put them in the vbr region and wait for the copy */
.gint.blocks : {
KEEP(*(.gint.blocks));
} > rom
/* Driver data going to ROM:
- Exposed driver interfaces (.gint.drivers)
The driver information is required to start and configure the
driver, even if the symbols are not referenced */
.gint.drivers : {
_bdrv = . ;
KEEP(*(.gint.drivers.0));
KEEP(*(.gint.drivers.1));
KEEP(*(.gint.drivers.2));
KEEP(*(.gint.drivers.3));
KEEP(*(.gint.drivers.4));
KEEP(*(.gint.drivers.5));
KEEP(*(.gint.drivers.6));
_edrv = . ;
} > rom
/* Read-only data going to ROM:
- Resources or assets from fxconv or similar converters
- Data marked read-only by the compiler (.rodata and .rodata.*) */
.rodata : SUBALIGN(4) {
/* Put these first, they need to be 4-aligned */
*(.rodata.4)
*(.rodata .rodata.*)
} > rom
/*
** RAM sections
*/
. = ORIGIN(ram);
/* BSS stuff going to RAM:
- Data marked BSS by the compiler
- BSS sections from fxlib, namely "B" and "R"
The BSS section is to be stripped from the ELF file later, and wiped
at startup. */
.bss (NOLOAD) : {
_rbss = . ;
*(.bss COMMON)
*(B R)
. = ALIGN(16);
} > ram :NONE
_sbss = SIZEOF(.bss);
/* Read-write data going to RAM:
- Data sections generated by the compiler (.data and .data.*)
- Data sections from fxlib, "D" */
.data ALIGN(4) : ALIGN(4) {
_ldata = LOADADDR(.data);
_rdata = . ;
*(.data .data.*)
*(D)
. = ALIGN(16);
} > ram AT> rom
/* Read-write data sub-aligned to 4 bytes (mainly from fxconv) */
.data.4 : SUBALIGN(4) {
*(.data.4)
. = ALIGN(16);
} > ram AT> rom
_sdata = SIZEOF(.data) + SIZEOF(.data.4);
/* On-chip memory sections: IL, X and Y memory */
. = ORIGIN(ilram);
.ilram ALIGN(4) : ALIGN(4) {
_lilram = LOADADDR(.ilram);
_rilram = . ;
*(.ilram)
. = ALIGN(16);
} > ilram AT> rom
. = ORIGIN(xram);
.xram ALIGN(4) : ALIGN(4) {
_lxram = LOADADDR(.xram);
_rxram = . ;
*(.xram)
. = ALIGN(16);
} > xram AT> rom
. = ORIGIN(yram);
.yram ALIGN(4) : ALIGN(4) {
_lyram = LOADADDR(.yram);
_ryram = . ;
*(.yram)
. = ALIGN(16);
} > yram AT> rom
_silram = SIZEOF(.ilram);
_sxram = SIZEOF(.xram);
_syram = SIZEOF(.yram);
/*
** RRAM sections
** 8800e000:5k VBR space
** 8800f400:3k .gint.data and .gint.bss
*/
/* VBR address: let's just start at the beginning of the RRAM area.
There's an unused 0x100-byte gap at the start of the VBR space.
The VBR space is already a large block (> 2 kiB), so I'm cutting off
the gap to spare some memory */
_gint_vbr = 0x8800df00;
. = ORIGIN(rram);
/* gint's data section, going to Real RAM. This section contains many
small objects from the library (static/global variables, etc) */
.gint.data ALIGN(4) : ALIGN(4) {
_lgdata = LOADADDR(.gint.data);
_rgdata = . ;
*(.gint.data .gint.data.*)
/* Also code that must remain permanently mapped! */
*(.gint.mapped)
. = ALIGN(16);
} > rram AT> rom
_sgdata = SIZEOF(.gint.data);
/* gint's uninitialized BSS section, going to Real RAM. All the large
data arrays will be located here */
.gint.bss (NOLOAD) : {
/* Since it's uninitialized, the location doesn't matter */
*(.gint.bss .gint.bss.*)
. = ALIGN(16);
} > rram :NONE
_sgbss = SIZEOF(.gint.bss);
/*
** Other sections
*/
/* Unwanted sections going to meet Dave Null:
- Debug sections, often come out of libgcc
- Java classes registration (why is there any of this here?)
- Asynchronous unwind tables: no C++ exception handling for now ^^
- Comments or anything the compiler might put in its assembler
- A stack section sometimes generated for build/version.o */
/DISCARD/ : {
*(.debug_info .debug_abbrev .debug_loc .debug_aranges
.debug_ranges .debug_line .debug_str)
*(.jcr)
*(.eh_frame_hdr)
*(.eh_frame)
*(.comment)
}
}