Re: [PULL -tip] x86: replacing mp_config_X with mpc_X
From: Ingo Molnar
Date: Mon Jan 12 2009 - 08:11:43 EST
* Jaswinder Singh Rajput <jaswinder@xxxxxxxxxxxxx> wrote:
> -struct mp_config_ioapic {
> - unsigned long mp_apicaddr;
> - unsigned int mp_apicid;
> - unsigned char mp_type;
> - unsigned char mp_apicver;
> - unsigned char mp_flags;
> -};
> -
> -struct mp_config_intsrc {
> - unsigned int mp_dstapic;
> - unsigned char mp_type;
> - unsigned char mp_irqtype;
> - unsigned short mp_irqflag;
> - unsigned char mp_srcbus;
> - unsigned char mp_srcbusirq;
> - unsigned char mp_dstirq;
> -};
So you replaced that with mpc_ioapic and mpc_intsrc uses:
struct mpc_ioapic {
unsigned char type;
unsigned char apicid;
unsigned char apicver;
unsigned char flags;
unsigned int apicaddr;
};
struct mpc_intsrc {
unsigned char type;
unsigned char irqtype;
unsigned short irqflag;
unsigned char srcbus;
unsigned char srcbusirq;
unsigned char dstapic;
unsigned char dstirq;
};
And removed the mp_config_ioapic and mp_config_intsrc types.
The mp_config_ioapic and mp_config_intsrc types are kernel-internal, while
mpc_ioapic and mpc_intsrc is an MP Specification type - the lowlevel
structure of these tables as provided in RAM or ROM by the BIOS.
Here's the potential problems that need to be thought through:
- the biggest potential problem is that apicaddr is 32-bit wide while
mp_apicaddr is 64-bit wide, on the 64-bit kernel. Can an apic address be
above 4 GB, in an mptable? I dont think it can be.
- another problem could be that dstapic are all 1-byte entities - while in
the in-kernel version (mp_apicid and mp_dstapic) they are 32 bit. The
ACPI code fills in the tables too so maybe there it can be wider than 8
bits?
I've Cc:-ed a few more folks.
The cleanup potential is significant: we can get rid of all the type
mixing that we do (assign_to_mp_irq(), assign_to_mpc_intsrc() can go away,
etc.) and can standardize the code.
Ingo
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