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What does the cmd "boot_regs: .space 32*4" mean?

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Applicable Environment

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Topic: What does the cmd "boot_regs: .space 32*4" mean?
SDP: 6.4.1
Target: Any supported target

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Issue / Question

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In the file : startup/lib/ppc/cstart.s
What does the cmd "boot_regs: .space 32*4" mean?
What is the reg "boot_regs" used for?

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Solution / Recommendation

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It reserves space for saving the 32 4 byte GPR contents. Some ROM monitors pass information in the registers when they transfer control to startup. The startup saves the initial register values so that routines later on can see what they were and make use of them (e.g. of_call() in openfirmware.c).

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NOTE: This entry has been validated against the SDP version listed above. Use caution when considering this advice for any other SDP version. For supported releases, please reach out to QNX Technical Support if you have any questions/concerns.

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