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Handle the case of an identity phys-to-virt mapping

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git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@2902 42af7a65-404d-4744-a932-0658087f49c3
This commit is contained in:
patacongo 2010-08-31 19:57:41 +00:00
parent 41e5689c0c
commit d494bce42b
1 changed files with 59 additions and 10 deletions
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69
arch/arm/src/arm/up_head.S
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@ -71,7 +71,16 @@
#ifdef CONFIG_BOOT_RUNFROMFLASH
# error "Configuration not implemented"
# define CONFIGURE_SDRAM
# define CONFIG_SDRAM 1
/* Check for the identity mapping: For this configuration, this would be
* the case where the section containing the NuttX entry virtual address
* is the same as the physcal beginning of FLASH.
*/
# if CONFIG_FLASH_START == (CONFIG_DRAM_NUTTXENTRY & 0xfff00000)
# define CONFIG_IDENTITY_TEXTMAP 1
# endif
/* 2. We boot in FLASH but copy ourselves to DRAM from better performance.
* (CONFIG_BOOT_RUNFROMFLASH=n && CONFIG_BOOT_COPYTORAM=y). In this case
@ -80,19 +89,41 @@
* - Configure SDRAM,
* - Copy ourself to DRAM (after mapping it), and
* - Clear .bss section
*
* In this case, we assume that the logic within this file executes from FLASH.
*/
#elif defined(CONFIG_BOOT_COPYTORAM)
# error "configuration not implemented
# define CONFIG_SDRAM
# define CONFIG_SDRAM 1
/* Check for the identity mapping: For this configuration, this would be
* the case where the section containing the NuttX entry virtual address
* is the same as the physcal beginning of FLASH.
*/
# if CONFIG_FLASH_START == (CONFIG_DRAM_NUTTXENTRY & 0xfff00000)
# define CONFIG_IDENTITY_TEXTMAP 1
# endif
/* 3. There is bootloader that copies us to DRAM (but probably not to the beginning)
* (CONFIG_BOOT_RUNFROMFLASH=n && CONFIG_BOOT_COPYTORAM=n). In this case the
* boot logic must:
* (CONFIG_BOOT_RUNFROMFLASH=n && CONFIG_BOOT_COPYTORAM=n). In this case SDRAM
* was initialized by the boot loader, and this boot logic must:
*
* - Clear .bss section
*/
#else
/* Check for the identity mapping: For this configuration, this would be
* the case where the section containing the NuttX entry virtual address
* is the same as the physcal beginning of RAM.
*/
# if CONFIG_DRAM_START == (CONFIG_DRAM_NUTTXENTRY & 0xfff00000)
# define CONFIG_IDENTITY_TEXTMAP 1
# endif
#endif
/****************************************************************************
@ -112,14 +143,26 @@
* Assembly Macros
****************************************************************************/
/* Since the page table is closely related to the NuttX base address, we can
* convert the page table base address to the base address of the section
* containing both.
/* The ARM9 L1 page table can be placed at the beginning or at the end of the
* RAM space. This decision is based on the placement of the vector area:
* If the vectors are place in low memory at address 0x0000 0000, then the
* page table is placed in high memory; if the vectors are placed in high
* memory at address 0xfff0 0000, then the page table is locating at the
* beginning of RAM.
*
* For the special case where (1) the program executes out of RAM, and (2) the
* page is located at the beginning of RAM, then the following macro can
* easily find the physical address of the section that includes the first
* part of the text region: Since the page table is closely related to the
* NuttX base address in this case, we can convert the page table base address
* to the base address of the section containing both.
*/
#ifndef CONFIG_ARCH_LOWVECTORS
.macro mksection, section, pgtable
bic \section, \pgtable, #0x000ff000
.endm
#endif
/* This macro will modify r0, r1, r2 and r14 */
@ -171,13 +214,17 @@ __start:
/* Create identity mapping for first MB of the .text section to support
* this startup logic executing out of the physical address space. This
* identity mapping will be removed by .Lvstart (see below).
* identity mapping will be removed by .Lvstart (see below). Of course,
* we would only do this if the physical-virtual mapping is not already
* the identity mapping.
*/
#ifndef CONFIG_IDENTITY_TEXTMAP
mksection r0, r4 /* r0=phys. base section */
ldr r1, .LCmmuflags /* FLGS=MMU_MEMFLAGS */
add r3, r1, r0 /* r3=flags + base */
str r3, [r4, r0, lsr #18] /* identity mapping */
#endif
#ifdef CONFIG_PAGING
/* Map the read-only .text region in place. This must be done
@ -399,17 +446,19 @@ __start:
.type .Lvstart, %function
.Lvstart:
/* Remove the temporary mapping. The following assumes that the
* total RAM size is > 1Mb and extends that initial mapping to
/* Remove the temporary mapping (if one was made). The following assumes
* that the total RAM size is > 1Mb and extends that initial mapping to
* cover additinal RAM sections.
*/
#ifndef CONFIG_ARCH_ROMPGTABLE
#ifndef CONFIG_IDENTITY_TEXTMAP
ldr r4, .LCvpgtable /* r4=virtual page table */
ldr r1, .LCppgtable /* r1=phys. page table */
mksection r3, r1 /* r2=phys. base addr */
mov r0, #0 /* flags + base = 0 */
str r0, [r4, r3, lsr #18] /* Undo identity mapping */
#endif
#if defined(CONFIG_PAGING)
/* Populate the L1 table for the data region */