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Gigabeat S: Update some very stale comments about what's going on in the startup code.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@19965 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2009-02-10 15:48:48 +00:00
parent 609157a145
commit e46309fde3
1 changed files with 8 additions and 10 deletions
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18
firmware/target/arm/imx31/crt0.S
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@ -43,21 +43,19 @@ start:
*
*/
/* Initially this code is running at VA 0x8a000000 (PA 0x82000000).
* The mapping stub is copied to IRAM (0x1fffc000) and jumps to the final
* VA remapping starting at 0x01f00000 because the 1MB section containing
* the framebuffer at PA 0x81000000 is skipped in the remapping giving 63MB
* of contiguous RAM for the firmware. The TTB is placed at the end of said
* section.
/* Bootloader:
* Initially this code is running at VA 0x8a000000 (PA 0x82000000).
* The mapping stub is copied to IRAM (0x1fffc000), sets up the MMU and
* jumps into the final VA remapping starting at 0x02000000 (32MB).
*
* For now this will be done in bootloader, especially if usb will be needed
* within the bootloader to load the main firmware file. Interrupts will be
* needed for this (whether they be swi or irq).
* Firmware:
* This code will be running from VA 0x00000000 (PA 0x80000000) and perform
* similar steps to the bootloader code.
*/
newstart:
msr cpsr_c, #0xd3 /* enter supervisor mode, disable IRQ/FIQ */
adr r2, remap_start /* Load PC-relative labels */
adr r2, remap_start /* Load PC-relative labels (relocatable) */
adr r3, remap_end
ldr r5, =TTB_BASE_ADDR /* TTB pointer */
ldr r6, =IRAM_BASE_ADDR