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Message-ID: <E717642AF17E744CA95C070CA815AE55B7E19A@cceexc23.americas.cpqcorp.net>
Date: Fri, 27 Oct 2006 10:15:18 -0500
From: "Miller, Mike (OS Dev)" <Mike.Miller@...com>
To: "Cameron, Steve" <steve.cameron@...com>,
"Randy Dunlap" <randy.dunlap@...cle.com>,
"Roland Dreier" <rdreier@...co.com>
Cc: "Andrew Morton" <akpm@...l.org>,
"ISS StorageDev" <iss_storagedev@...com>,
"lkml" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH cciss: fix printk format warning
> -----Original Message-----
> From: Cameron, Steve
> Sent: Friday, October 27, 2006 8:12 AM
> To: Randy Dunlap; Roland Dreier
> Cc: Andrew Morton; ISS StorageDev; lkml
> Subject: RE: [PATCH cciss: fix printk format warning
>
> > Roland Dreier wrote:
> > > > > if (*total_size != (__u32) 0)
> > > >
> > > > Why is cciss_read_capacity casting *total_size to u32?
> > >
> > > It's not -- it's actually casting 0 to __32 -- there's no cast on
> > > the *total_size side of the comparison. However that
> just makes the
> > > cast look even fishier.
If the volume is >2TB read_capacity will return 8 F's. We've already
added 1 to total_size which equals 0. I only care if the lower 32 bits
are zero so that's the reason for the cast.
Does that make sense or am I out in the weeds?
mikem
> > >
> > > - R.
> >
> > OK, how about this one then?
> >
> >
> > c->busaddr = (__u32) cmd_dma_handle;
> >
> > where cmd_dma_handle is a dma_addr_t (u32 or u64)
>
> The command register to which that value is written is a 32
> bit register. Cast it or not, only 32 bits will be used.
> The DMA mask used to get that memory should ensure it's 32
> bit addressable.
>
> > and then later:
> >
> > pci_free_consistent(h->pdev, sizeof(CommandList_struct),
> > c, (dma_addr_t) c->busaddr);
>
>
>
>
>
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