On Sat, Dec 17, 2016 at 11:52:05AM -0600, Larry Finger wrote:
> Upon examination of the routine, I can see that if purgatory() should be
> static, then none of the code here will ever be accessed by any part of the
> kernel. Is there some bit of magic that is above my understanding, or is
> this a useless bit of code that has been forgotten and should be removed?
I don't know what is and what is not above your understanding, but grepping
in that area (grep -w purgatory arch/x86/purgatory/*) does catch this:
arch/x86/purgatory/setup-x86_64.S: call purgatory
which is hardly magic - looks like a function call. Looking into that
file shows
purgatory_start:
.code64
/* Load a gdt so I know what the segment registers are */
lgdt gdt(%rip)
/* load the data segments */
movl $0x18, %eax /* data segment */
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
movl %eax, %fs
movl %eax, %gs
/* Setup a stack */
leaq lstack_end(%rip), %rsp
/* Call the C code */
call purgatory
jmp entry64
which pretty much confirms that - it's called from purgatory_start().
