tegra20: add back USE_PRIVATE_LIBGCC

As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to use USE_PRIVATE_LIBGCC still.

However commit 5286f1ce dropped it regardless. Adding this back fixes a hang while handing over from SPL to U-Boot on Colibri T20.

Quoted 5 lines

As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to use USE_PRIVATE_LIBGCC still.

However commit 5286f1ce dropped it regardless. Adding this back fixes a hang while handing over from SPL to U-Boot on Colibri T20.

This probably makes sense, but Allen should comment on this.

I wonder why I haven't seen any issue with this; perhaps SPL on all the boards I tested ended up not using any libgcc functions? But in that case, why would the Colibri board end up using them?

Am Dienstag, den 07.08.2012, 11:00 -0600 schrieb Stephen Warren:

Quoted 13 lines · Lucas Stach

Quoted 5 lines

As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to use USE_PRIVATE_LIBGCC still.

However commit 5286f1ce dropped it regardless. Adding this back fixes a hang while handing over from SPL to U-Boot on Colibri T20.

This probably makes sense, but Allen should comment on this.

I wonder why I haven't seen any issue with this; perhaps SPL on all the boards I tested ended up not using any libgcc functions? But in that case, why would the Colibri board end up using them?

Could also be a toolchain issue. My normal workflow uses a toolchain without a libgcc, as we didn't needed it to this point. After porting over my changes to the new SPL boot I had to switch to a CodeSourcery toolchain containing a libgcc. So I'm not entirely sure where the problem lies, as I varied codebase and toolchain at one. But I confirmed that this patch works with both of my toolchains.

So yes, I'm really in favour of some comments.

Quoted 14 lines

Am Dienstag, den 07.08.2012, 11:00 -0600 schrieb Stephen Warren:

Quoted 13 lines · Lucas Stach

Quoted 5 lines

As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to use USE_PRIVATE_LIBGCC still.

However commit 5286f1ce dropped it regardless. Adding this back fixes a hang while handing over from SPL to U-Boot on Colibri T20.

This probably makes sense, but Allen should comment on this.

I wonder why I haven't seen any issue with this; perhaps SPL on all the boards I tested ended up not using any libgcc functions? But in that case, why would the Colibri board end up using them?

Quoted 8 lines

Could also be a toolchain issue. My normal workflow uses a toolchain without a libgcc, as we didn't needed it to this point. After porting over my changes to the new SPL boot I had to switch to a CodeSourcery toolchain containing a libgcc. So I'm not entirely sure where the problem lies, as I varied codebase and toolchain at one. But I confirmed that this patch works with both of my toolchains.

So yes, I'm really in favour of some comments.

What's the CodeSourcery toolchain you're using? The USE_PRIVATE_LIBGCC was used to prevent armv5 instructions from the toolchain's libgcc from getting into the code that executes on the AVP which is an arm7tdmi (armv4t). Since all the code that runs on the AVP is built separately now as part of the SPL, using the toolchain's libgcc should work for the main u-boot build. USE_PRIVATE_LIBGCC is still turned on for the SPL build.

I've tested the following toolchains on ventana and seaboard tegra20 platforms:

gcc 4.4.6 arm7tdmi-linux-gnueabi built with crosstool-ng gcc 4.4.6 cortex_a9-linux-gnueabi built with crosstool-ng gcc 4.6.1 cortex_a9-linux-gnueabi built with crosstool-ng

Tell me what CodeSourcery version you're using and I'll test it here as well and see if I can reproduce the problem.

Hi Allen,

Quoted 3 lines

Tell me what CodeSourcery version you're using and I'll test it here as well and see if I can reproduce the problem.

I used CodeSourcery arm-2011.09-70-arm-none-linux-gnueabi to test this.

And to answer Tom's question: the failure was that the real U-Boot would not come up after the SPL. All I could see was the one line printed by the SPL and nothing more.

Hi Allen,

And to answer Tom's question: the failure was that the real U-Boot would not come up after the SPL. All I could see was the one line printed by the SPL and nothing more.

Quoted 5 lines

Hi Allen,

And to answer Tom's question: the failure was that the real U-Boot would not come up after the SPL. All I could see was the one line printed by the SPL and nothing more.

I think I found the problem. It's the following code from start.S:

ENTRY(cpu_init_crit)
/*
* Jump to board specific initialization...
* The Mask ROM will have already initialized
* basic memory. Go here to bump up clock rate and handle
* wake up conditions.
*/
mov ip, lr @ persevere link reg across
call
bl lowlevel_init @ go setup pll,mux,memory
mov lr, ip @ restore link
mov pc, lr @ back to my caller
ENDPROC(cpu_init_crit)

The "ip" register is not preserved across function calls, and the CodeSourcery compiler is using it in lowlevel_init or one of the functions it calls. This code was there before the SPL changes, but wasn't being called because CONFIG_SKIP_LOWLEVEL_INIT was set, but now it isn't.

Lucas, can you try the following change? I tested it on seaboard with CodeSourcery arm-2011.09-70-arm-none-linux-gnueabi and I'm able to boot a kernel.

Tom if this works we probably want to get it into your pull request to Albert. CodeSourcery toolchain is probably used by a lot of people.

(quoted diff) +0 -1

-Allen

arch/arm/cpu/armv7/start.S +1 -25

index 2506f27..02e47fa 100644
@@ -152,7 +152,7 @@ reset:
        /* the mask ROM code should have PLL and others stable */
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
        bl      cpu_init_cp15
-       bl      cpu_init_crit
+       bl      lowlevel_init           @ go setup pll,mux,memory
 #endif
 
 /* Set stackpointer in internal RAM to call board_init_f */

@@ -339,29 +339,6 @@ ENTRY(cpu_init_cp15)
        mov     pc, lr                  @ back to my caller
 ENDPROC(cpu_init_cp15)
 
-#ifndef CONFIG_SKIP_LOWLEVEL_INIT
-/*************************************************************************
- *
- * CPU_init_critical registers
- *
- * setup important registers
- * setup memory timing
- *
- *************************************************************************/
-ENTRY(cpu_init_crit)
-       /*
-        * Jump to board specific initialization...
-        * The Mask ROM will have already initialized
-        * basic memory. Go here to bump up clock rate and handle
-        * wake up conditions.
-        */
-       mov     ip, lr                  @ persevere link reg across
-call
-       bl      lowlevel_init           @ go setup pll,mux,memory
-       mov     lr, ip                  @ restore link
-       mov     pc, lr                  @ back to my caller
-ENDPROC(cpu_init_crit)
-#endif
-
 #ifndef CONFIG_SPL_BUILD
 /*
  *************************************************************************

Am Dienstag, den 07.08.2012, 15:28 -0700 schrieb Allen Martin:

Quoted 30 lines · Lucas Stach

Quoted 5 lines

Hi Allen,

And to answer Tom's question: the failure was that the real U-Boot would not come up after the SPL. All I could see was the one line printed by the SPL and nothing more.

I think I found the problem. It's the following code from start.S:

ENTRY(cpu_init_crit)
/*
* Jump to board specific initialization...
* The Mask ROM will have already initialized
* basic memory. Go here to bump up clock rate and handle
* wake up conditions.
*/
mov ip, lr @ persevere link reg across
call
bl lowlevel_init @ go setup pll,mux,memory
mov lr, ip @ restore link
mov pc, lr @ back to my caller
ENDPROC(cpu_init_crit)

The "ip" register is not preserved across function calls, and the CodeSourcery compiler is using it in lowlevel_init or one of the functions it calls. This code was there before the SPL changes, but wasn't being called because CONFIG_SKIP_LOWLEVEL_INIT was set, but now it isn't.

Quoted 3 lines

Lucas, can you try the following change? I tested it on seaboard with CodeSourcery arm-2011.09-70-arm-none-linux-gnueabi and I'm able to boot a kernel.

Yes I can confirm this fixes the issue without further workarounds. Thanks, and:

Tested-by Lucas Stach <[email protected]>

As discussed here [http://patchwork.ozlabs.org/patch/158202/] we want to use USE_PRIVATE_LIBGCC still.

However commit 5286f1ce dropped it regardless. Adding this back fixes a hang while handing over from SPL to U-Boot on Colibri T20.

Signed-off-by Lucas Stach <[email protected]>

CC Stephen Warren <[email protected]>

CC Tom Warren <[email protected]>

---
 arch/arm/cpu/armv7/tegra20/config.mk | 2 ++

1 Datei ge?ndert, 2 Zeilen hinzugef?gt(+)

arch/arm/cpu/armv7/tegra20/config.mk +0 -0

index 6432e75..e666f6b 100644