Re: [PATCH 10/12] ARM: add early malloc support needed by the decompressor

From: Sascha Hauer <s.hauer@pengutronix.de>
To: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Cc: barebox@lists.infradead.org
Subject: Re: [PATCH 10/12] ARM: add early malloc support needed by the decompressor
Date: Mon, 30 Jul 2012 10:59:35 +0200	[thread overview]
Message-ID: <20120730085935.GO30009@pengutronix.de> (raw)
In-Reply-To: <20120730084943.GA19759@game.jcrosoft.org>

On Mon, Jul 30, 2012 at 10:49:43AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> On 10:30 Mon 30 Jul     , Sascha Hauer wrote:
> > On Mon, Jul 30, 2012 at 10:19:42AM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > On 10:02 Mon 30 Jul     , Sascha Hauer wrote:
> > > > On Fri, Jul 27, 2012 at 08:33:08PM +0200, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > > > This is not needed by lzo but by gunzip, xz and others.
> > > > > 
> > > > > Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
> > > > > ---
> > > > >  arch/arm/cpu/start.c |    7 +++++++
> > > > >  1 file changed, 7 insertions(+)
> > > > > 
> > > > > diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
> > > > > index a54f5fd..f500ca8 100644
> > > > > --- a/arch/arm/cpu/start.c
> > > > > +++ b/arch/arm/cpu/start.c
> > > > > @@ -28,6 +28,9 @@
> > > > >  #include <asm-generic/memory_layout.h>
> > > > >  #include <asm/sections.h>
> > > > >  
> > > > > +unsigned long free_mem_ptr;
> > > > > +unsigned long free_mem_end_ptr;
> > > > > +
> > > > >  #ifdef CONFIG_PBL_IMAGE
> > > > >  void __naked __section(.text_head_entry) pbl_start(void)
> > > > >  {
> > > > > @@ -193,6 +196,10 @@ void __naked __section(.text_ll_return) board_init_lowlevel_return(void)
> > > > >  	/* clear bss */
> > > > >  	memset(__bss_start, 0, __bss_stop - __bss_start);
> > > > >  
> > > > > +	/* set 128 KiB before the STACK_BASE - 16 address for early malloc */
> > > > > +	free_mem_ptr = STACK_BASE - 0x20000 - 16;
> > > > > +	free_mem_end_ptr = STACK_BASE - 16;
> > > > > +
> > > > 
> > > > This assumes that the malloc area is directly before the stack. How
> > > > about using __bss_stop or _end instead?
> > > 
> > > it's just for early alloc and __bss_stop no so maybe we can use the same as
> > > Malloc but we already use this for HEAD_TEXT_BASE
> > 
> > _end is HEAD_TEXT_BASE + the space needed for the compressed
> > image, so what's wrong with it?
> the pbl image can be stored in a sram and link to fit there so _end could be
> at the end of the sram
> 
> so we can not use it.
> 
> We need to put the early malloc in the sdram

HEAD_TEXT_BASE is in sdram, because it's the same as MALLOC_BASE, so
_end by definition also is in sdram.

Sascha

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