[SeaBIOS] [PATCH 0/5] SMM improvements

[Kevin O'Connor]

On Thu, May 15, 2014 at 06:36:08PM +0200, Paolo Bonzini wrote:
> A simple way to reconcile the C code with the changes I'm making could be to
> make the relocation code associated to one particular value of APMC.

It's not hard to pass in the %cs segment to the C code - this works
(with some other minor changes):

-// ljmpw $SEG_BIOS, $(entry_smi - BUILD_BIOS_ADDR)
-#define SMI_INSN (0xea | ((u64)SEG_BIOS<<24) \
-                  | (((u32)entry_smi - BUILD_BIOS_ADDR) << 8))
+// movw %cs, %ax; ljmpw $SEG_BIOS, $(entry_smi - BUILD_BIOS_ADDR)
+#define SMI_INSN (0xeac88c | ((u64)SEG_BIOS<<40) \
+                  | ((u64)((u32)entry_smi - BUILD_BIOS_ADDR) << 24))

[...]
> smm_handler(void *smbase)
> {
>     switch (inb(0xb2)) {
>     case 0xAA:
>         if (smbase != (void *)0xA0000L) {
> 	    ...
> 	}
> 	outb(PORT_SMI_STATUS, 0);
>     }
>     outl(smm_eos_port, inl(smm_eos_port)|smm_eos_value);
>     outl(smm_status_port, smm_status_value);
> }
> 
> I think this is more easily visible on top of these patches more than the
> other way round, but I'm biased of course...

I was referring to your patch 5, which adds a bunch of assembler
variables - I think it would be clearer to add them in C to start.

-Kevin