[PATCH] aic7xxx large integer

[PATCH] aic7xxx large integer

[Miguel Angel Flores]

[-- Attachment #1: Type: text/plain, Size: 133 bytes --]

Hi all,

I noticed a large integer warning when compiling 2.6.10rc3 with the SCSI 
AIC-7xxx driver.

Here is the patch.

Cheers,
MaF

[-- Attachment #2: patch-aic7xxx --]
[-- Type: text/plain, Size: 553 bytes --]

diff -r -u linux-2.6.10-rc3/drivers/scsi/aic7xxx/aic7xxx_osm_pci.c linux-2.6.10-rc3-maf/drivers/scsi/aic7xxx/aic7xxx_osm_pci.c
--- linux-2.6.10-rc3/drivers/scsi/aic7xxx/aic7xxx_osm_pci.c	2004-12-04 20:48:11.000000000 +0100
+++ linux-2.6.10-rc3-maf/drivers/scsi/aic7xxx/aic7xxx_osm_pci.c	2004-12-04 20:37:54.000000000 +0100
@@ -226,7 +226,7 @@
 	}
 	pci_set_master(pdev);
 
-	mask_39bit = 0x7FFFFFFFFFULL;
+	mask_39bit = 0x7FFFFFFF;
 	if (sizeof(dma_addr_t) > 4
 	 && ahc_linux_get_memsize() > 0x80000000
 	 && pci_set_dma_mask(pdev, mask_39bit) == 0) {

Re: [PATCH] aic7xxx large integer

[Dr. David Alan Gilbert]

* Miguel Angel Flores (maf@sombragris.com) wrote:
> Hi all,
> 
> I noticed a large integer warning when compiling 2.6.10rc3 with the SCSI 
> AIC-7xxx driver.
>  
> -	mask_39bit = 0x7FFFFFFFFFULL;
> +	mask_39bit = 0x7FFFFFFF;

Hmm - I can't help but think that perhaps
'mask_39bit' was intended to be a 39 bit mask.

Dave

 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    | Running GNU/Linux on Alpha,68K| Happy  \ 
\ gro.gilbert @ treblig.org | MIPS,x86,ARM,SPARC,PPC & HPPA | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/

Re: [PATCH] aic7xxx large integer

[Robert Love]

On Sat, 2004-12-04 at 21:49 +0100, Miguel Angel Flores wrote:

> -	mask_39bit = 0x7FFFFFFFFFULL;
> +	mask_39bit = 0x7FFFFFFF;

I cannot believe that this is the correct solution and, if it is, the
name of the variable ought to be changed.

More likely, I suspect that the mask wants to be 39-bits, what with its
name and all.

The problem is that DMA addresses come in both 32-bit (generic) and
64-bit (high) forms.  mask_39bit is a dma_addr_t so it is 64-bit if
CONFIG_HIGHMEM64G and 32-bit otherwise.  Possibly, the right solution is
to make mask_39bit dma64_addr_t.  Or, if the mapping needs to be
consistent, assign a different value depending on the value of
CONFIG_HIGHMEM64G.

See Documentation/DMA-*.txt for more information.

	Robert Love

Re: [PATCH] aic7xxx large integer

[Miguel Angel Flores]

Miguel Angel Flores wrote:

> Hi all,
>
> I noticed a large integer warning when compiling 2.6.10rc3 with the 
> SCSI AIC-7xxx driver.
>
> Here is the patch.
>
> Cheers,
> MaF

I post the patch very quickly :(. The original code finally seems OK. My 
controller is not working with 39 bit addressing, although I can't find 
why the compiler warns. Maybe the length of dma_addr_t type, in the 
2.6.9 the type of the mask_39bit variable is bus_addr_t.

Forget the patch. I'll continue looking...

Thanks and excuse the inconvenience.

Cheers,
MaF

Re: [PATCH] aic7xxx large integer

[Robert Love]

On Sun, 2004-12-05 at 00:16 +0100, Miguel Angel Flores wrote:

> I post the patch very quickly :(. The original code finally seems OK. My 
> controller is not working with 39 bit addressing, although I can't find 
> why the compiler warns. Maybe the length of dma_addr_t type, in the 
> 2.6.9 the type of the mask_39bit variable is bus_addr_t.

The compiler warns because you are putting a 64-bit value (an unsigned
long long) in a 32-bit value (a u32).

There is definitely a problem on non-highmem compiled kernels, there is
no doubt of that.  The concern was that your suggested fix is not right.

Assuming that a 39-bit value is really wanted, the type either needs to
be changed to a dma64_addr_t or the value needs to change at
compile-time to a suitable 32-bit variant when !CONFIG_HIGHMEM64G.

Without knowing what the driver is doing, I have no idea.

	Robert Love

Re: [PATCH] aic7xxx large integer

[H. Peter Anvin]

Followup to:  <1102208526.6052.87.camel@localhost>
By author:    Robert Love <rml@novell.com>
In newsgroup: linux.dev.kernel
>
> On Sun, 2004-12-05 at 00:16 +0100, Miguel Angel Flores wrote:
> 
> > I post the patch very quickly :(. The original code finally seems OK. My 
> > controller is not working with 39 bit addressing, although I can't find 
> > why the compiler warns. Maybe the length of dma_addr_t type, in the 
> > 2.6.9 the type of the mask_39bit variable is bus_addr_t.
> 
> The compiler warns because you are putting a 64-bit value (an unsigned
> long long) in a 32-bit value (a u32).
> 
> There is definitely a problem on non-highmem compiled kernels, there is
> no doubt of that.  The concern was that your suggested fix is not right.
> 
> Assuming that a 39-bit value is really wanted, the type either needs to
> be changed to a dma64_addr_t or the value needs to change at
> compile-time to a suitable 32-bit variant when !CONFIG_HIGHMEM64G.
> 
> Without knowing what the driver is doing, I have no idea.
> 

I suspect that what the driver wants is a mask that is a valid DMA
address no wider than 39 bits (because that's all the hardware can
do.)

If so, I would assume (dma_addr_t)0x7FFFFFFFFFULL is probably the
right thing; it will be truncated to a 32-bit mask if only 32-bit
addressing is available.

	-hpa