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Re: [PATCH gnumach] smp: Remove hardcoded AP_BOOT_ADDR
From: |
Damien Zammit |
Subject: |
Re: [PATCH gnumach] smp: Remove hardcoded AP_BOOT_ADDR |
Date: |
Tue, 30 Jan 2024 01:55:32 +0000 |
Hi Samuel,
On 1/29/24 9:20 PM, Samuel Thibault wrote:
> Damien Zammit, le lun. 29 janv. 2024 10:07:30 +0000, a ecrit:
>> - ljmp $BOOT_CS, $M(0f)
>> + xorl %eax, %eax
>> + mov %cs, %ax
>> + shll $4, %eax
>> + addl $M(0f), %eax
>> + movl %eax, M(ljmp_offset32)
> This won't work with pipelined processors, which assume a complete
> separation between code and data, and will thus have already loaded
> the jmp instruction before your modify it.
>
> Rather either perform the relocation from the C code, or use a variable,
> which you can refer from the ljmp instruction.
I was unable to make the ljmpl instruction assemble with a memory location
as the second argument.
I don't know what to do, other than I could use a simple jmp instruction
to clear the instruction cache before doing the ljmpl?
Damien