[U-Boot-Users] PPC 405 _start code
Greetings:
I just build a version of u-boot for the PPC 405GP.
If I disassemble the code that is generated I see the following:
fff80100 <_start>: fff80100: 38 80 00 00 li r4,0 fff80104: 7c 99 eb a6 mtsgr r4 fff80108: 7c 9a eb a6 mtdcwr r4 fff8010c: 7c 94 f3 a6 mtesr r4 fff80110: 7c 9a f3 a6 mttcr r4 fff80114: 7c 81 03 a6 mtxer r4 fff80118: 7c 96 f3 a6 mtevpr r4 fff8011c: 38 80 10 00 li r4,4096
So to develop a deeper understanding of how all the pieces fit together I went to the start.S module under the cpu subdirecory. There I see the _start vector - however the code I see in start.S does not correspond to the code that I disassembled.
What am I missing?
Kindest Regards,
Jerry
sorry - I should clarify -
what I expect to see it what I see in /cpu/start.S which looks like:
.text .long 0x27051956 /* U-Boot Magic Number */ .globl version_string version_string: .ascii U_BOOT_VERSION .ascii " (", __DATE__, " - ", __TIME__, ")" .ascii CONFIG_IDENT_STRING, "\0"
/* * Maybe this should be moved somewhere else because the current * location (0x100) is where the CriticalInput Execption should be. */ . = EXC_OFF_SYS_RESET .globl _start _start: #if defined(CONFIG_405GP) || defined(CONFIG_405CR) || defined(CONFIG_405) *---------------------------------- */ /* Clear and set up some registers. */ /*--------------------------------- */ addi r4,r0,0x0000 mtspr sgr,r4 mtspr dcwr,r4
Instead I see:
fff80100 <_start>: fff80100: 38 80 00 00 li r4,0 fff80104: 7c 99 eb a6 mtsgr r4 fff80108: 7c 9a eb a6 mtdcwr r4 fff8010c: 7c 94 f3 a6 mtesr r4 fff80110: 7c 9a f3 a6 mttcr r4 fff80114: 7c 81 03 a6 mtxer r4 fff80118: 7c 96 f3 a6 mtevpr r4 fff8011c: 38 80 10 00 li r4,4096
So hence I am confused....
-----Original Message----- From: u-boot-users-admin@lists.sourceforge.net [mailto:u-boot-users-admin@lists.sourceforge.net]On Behalf Of Jerry Walden Sent: Saturday, December 14, 2002 11:49 AM To: u-boot-users@lists.sourceforge.net Subject: [U-Boot-Users] PPC 405 _start code
Greetings:
I just build a version of u-boot for the PPC 405GP.
If I disassemble the code that is generated I see the following:
fff80100 <_start>: fff80100: 38 80 00 00 li r4,0 fff80104: 7c 99 eb a6 mtsgr r4 fff80108: 7c 9a eb a6 mtdcwr r4 fff8010c: 7c 94 f3 a6 mtesr r4 fff80110: 7c 9a f3 a6 mttcr r4 fff80114: 7c 81 03 a6 mtxer r4 fff80118: 7c 96 f3 a6 mtevpr r4 fff8011c: 38 80 10 00 li r4,4096
So to develop a deeper understanding of how all the pieces fit together I went to the start.S module under the cpu subdirecory. There I see the _start vector - however the code I see in start.S does not correspond to the code that I disassembled.
What am I missing?
Kindest Regards,
Jerry
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In message EGEGIJHKDKJGAJMGIDPNOEHHCCAA.jwalden@digitalatlantic.com you wrote:
what I expect to see it what I see in /cpu/start.S which looks like:
.text .long 0x27051956 /* U-Boot Magic Number */ .globl version_string version_string: .ascii U_BOOT_VERSION .ascii " (", __DATE__, " - ", __TIME__, ")" .ascii CONFIG_IDENT_STRING, "\0"
Let's ignore this part for now - you should find it at offset 0x0000. _start is at offset 0x0100:
_start:
...
addi r4,r0,0x0000 mtspr sgr,r4 mtspr dcwr,r4
Instead I see:
fff80100 <_start>: fff80100: 38 80 00 00 li r4,0 fff80104: 7c 99 eb a6 mtsgr r4 fff80108: 7c 9a eb a6 mtdcwr r4 fff8010c: 7c 94 f3 a6 mtesr r4 fff80110: 7c 9a f3 a6 mttcr r4 fff80114: 7c 81 03 a6 mtxer r4 fff80118: 7c 96 f3 a6 mtevpr r4 fff8011c: 38 80 10 00 li r4,4096
So hence I am confused....
You confuse me. Why are you confused?
"addi r4,r0,0x0000" == "li r4,0" "mtspr sgr,r4" == "mtsgr r4" "mtspr dcwr,r4" == "mtdcwr r4" ...
Looks identical to me.
Best regards,
Wolfgang Denk
participants (2)
-
Jerry Walden -
Wolfgang Denk