On 5/11/2011 10:08 AM, Jean Delvare wrote:
On Wed, 11 May 2011 16:28:04 +0200, Luca Tettamanti wrote:
On Wed, May 11, 2011 at 04:15:45PM +0200, Jean Delvare wrote:
On Wed, 11 May 2011 15:48:59 +0200, Luca Tettamanti wrote:
The driver uses lahf to copy the lowest byte of EFLAGS to eax, then
shifts it to right and test the lowest bit (CF).
Using pushf instead we get the whole EFLAGS and test the lowest bit.
Does it make sense? Someone should double check the patch, I don't trust
my assembly skills ;)
diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index d72433f..3554d10 100644
--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -139,8 +139,8 @@ static int i8k_smm(struct smm_regs *regs)
"movl %%edi,20(%%rax)\n\t"
"popq %%rdx\n\t"
"movl %%edx,0(%%rax)\n\t"
- "lahf\n\t"
- "shrl $8,%%eax\n\t"
+ "pusfh\n\t"
I think you meant pushf, not pusfh, right?
Yeah, right... hand me that brown paper bag ;)
+ "popl %%eax\n\t"
"andl $1,%%eax\n"
:"=a"(rc)
: "a"(regs)
I am no asm expert, but I don't get why you removed the shrl
instruction. As I understand it, your pushf+popl replaces only lahf,
the bit shifting is still needed (I assume the code wants to test bit 8
in the flag register.)
AFAIK lahf loads the lowest byte of EFLAGS into AH which is the upper
half of AX, hence the shift.
Yes, you're right, of course. So much for my asm skills. Please return
the brown paper bag to me when you're done ;)
The popl is wrong though, pushf only pushes 2 bytes... so let's try
again:
diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
index d72433f..f71f266 100644
--- a/drivers/char/i8k.c
+++ b/drivers/char/i8k.c
@@ -139,8 +139,8 @@ static int i8k_smm(struct smm_regs *regs)
"movl %%edi,20(%%rax)\n\t"
"popq %%rdx\n\t"
"movl %%edx,0(%%rax)\n\t"
- "lahf\n\t"
- "shrl $8,%%eax\n\t"
+ "pushf\n\t"
+ "pop %%ax\n\t"
"andl $1,%%eax\n"
:"=a"(rc)
: "a"(regs)
Looks reasonable. I can't test it as I don't have the hardware, but I
have updated the driver at:
http://khali.linux-fr.org/devel/misc/i8k/
with the above fix. Jeff, Harry, can you test?
Thanks,
Preliminary feedback...seeing new errors. New "i8k" module reporting 'no
such device' when inserted. More details to follow when I finish testing
and capture outputs.
_______________________________________________
lm-sensors mailing list
lm-sensors@xxxxxxxxxxxxxx
http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
