[tlinux-users:08144] Re: New release of omnibook module soon: testing welcome

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On Tue, 12 Sep 2006, Mathieu Bérard wrote:

> Holger Nelson a écrit :
> > Just another typo-fix:
> >
> >
> >   
> One word: Thanks
> One more fix like that an you have SVN commit access.
> 
> Could you please try this and check it doesn't introduce
> any regression:

It works, but I doubt it does what you really want:
The disassembly of your code shows:
intel_do_smi_call():
/home/crius/download/xx/xxxx/trunk/nbsmi.c:153
 3c2:   89 f0                   mov    %esi,%eax
 3c4:   9c                      pushf
 3c5:   60                      pusha
 3c6:   66 e7 b2                out    %ax,$0xb2
 3c9:   66 83 f8 00             cmp    $0x0,%ax
 3cd:   74 08                   je     3d7 <nbsmi_smi_command+0xad>
 3cf:   c7 44 24 0c fb ff ff    movl   $0xfffffffb,0xc(%esp)
 3d6:   ff
 3d7:   61                      popa
 3d8:   9d                      popf

Looking at the stack at 3cf will show something like (I dont know the 
stack-layout of pusha/popa nor exactly which registers get saved so I just 
guess as I am to lazy to look it up. ;-) )

esp+0x2c:retval
esp+0x28:???
esp:0x24:???
- ---- Flags by pushf:
esp+0x20:Flags
- ---- Registers by pusha:
esp+0x1c:eax
esp+0x18:ebx
esp+0x14:ecx
esp+0x10:edx
esp+0x0c:esi
esp+0x08:edi
esp+0x04:ebp
esp+0x02:es
esp+0x00:ds

So the assembly-Instruction at 3cf will change some register instead if 
retval. As retval is just a pointer to *retval, you also need to 
dereference it by something like:
	lea 0x2c(%esp),%bx
	mov $0xfffffffb,(%bx)

As little proof I modified 
	u32 retval=0;
to 
	u32 retval=255;
in nbsmi_smi_command and got the expected errors in dmesg:
[4350356.495000] omnibook: smi_command failed with error 255.

While I am at it another simple fix against R166:
As the structs are put on stack we cannot know that they are initialized 
with 0 so we need to initialize the used fields ourself.

- --- orig/nbsmi.c	2006-09-12 03:10:00.000000000 +0200
+++ trunk/nbsmi.c	2006-09-12 12:31:55.000000000 +0200
@@ -428,6 +428,7 @@ static int omnibook_nbsmi_get_wireless(c
 	u8 data;
 	
 	aerial_op.read_addr = SMI_GET_KILL_SWITCH;
+	aerial_op.read_mask = 0;
 
 	if((retval = nbsmi_smi_read_command(&aerial_op, &data)))
 		goto out;
@@ -475,6 +476,7 @@ static int omnibook_nbmsi_hotkeys_get(co
 	struct omnibook_operation hotkeys_op;
 	
 	hotkeys_op.read_addr = SMI_GET_FN_INTERFACE;
+	hotkeys_op.read_mask = 0;
 
 	retval = nbsmi_smi_read_command(&hotkeys_op, &data);
 	if(retval < 0)
@@ -529,6 +531,7 @@ static int  omnibook_nbmsi_display_get(c
 	struct omnibook_operation display_op;
 
 	display_op.read_addr = SMI_GET_DISPLAY_STATE;
+	display_op.read_mask = 0;
 
 	retval = nbsmi_smi_read_command(&display_op, &data);
 	if(retval < 0)

Holger
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