On Sat, 29 Mar 2008 14:09:29 -0400
Douglas Gilbert <dougg@xxxxxxxxxx> wrote:
> FUJITA Tomonori wrote:
> > Currently, the maximum amount of RAM that scsi_debug can allocate is
> > 4GB. This patch increases it to 2TB; scsi_debug can allocates 2TB
> > memory and export it as if it were 2TB scsi disk.
> >
> > Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> > Cc: Douglas Gilbert <dougg@xxxxxxxxxx>
> > Cc: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> > drivers/scsi/scsi_debug.c | 6 +++---
> > 1 files changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/scsi/scsi_debug.c b/drivers/scsi/scsi_debug.c
> > index c98559e..1b6a6d8 100644
> > --- a/drivers/scsi/scsi_debug.c
> > +++ b/drivers/scsi/scsi_debug.c
> > @@ -1949,7 +1949,7 @@ static void __init init_all_queued(void)
> > }
> >
> > static void __init sdebug_build_parts(unsigned char *ramp,
> > - unsigned int store_size)
> > + unsigned long store_size)
> > {
> > struct partition * pp;
> > int starts[SDEBUG_MAX_PARTS + 2];
> > @@ -2476,14 +2476,14 @@ static void do_remove_driverfs_files(void)
> >
> > static int __init scsi_debug_init(void)
> > {
> > - unsigned int sz;
> > + unsigned long sz;
> > int host_to_add;
> > int k;
> > int ret;
> >
> > if (scsi_debug_dev_size_mb < 1)
> > scsi_debug_dev_size_mb = 1; /* force minimum 1 MB ramdisk */
> > - sz = (unsigned int)scsi_debug_dev_size_mb * 1048576;
> > + sz = (unsigned long)scsi_debug_dev_size_mb * 1048576;
> > sdebug_store_sectors = sz / SECT_SIZE;
> > sdebug_capacity = get_sdebug_capacity();
> >
>
> Tomo,
> Unsigned long is 32 bits on i386 (and 64 bits in the LP64
> data model). Don't you want 64 bits in all cases? Either
> unsigned long long, uint64_t or one of those crappy
> kernel typedefs for 64 bits.
I don't think that u64 is useful.
scsi_debug uses vmalloc for logical unit's contents. so u32 is large
enough for 32-bit systems.
Even if we change scsi_debug use alloc_pages to allocate multiple
pages, 32-bit systems can have only several GB memory at most. So u32
is large enough for them in most cases. The advantage of vmalloc, a
continuous memory area, making the driver simpler a bit, is nice.
vmalloc takes unsigned long so I changed 'unsigned int' to 'unsigned
long' here.
In the end, you need a 64-bit system if you want scsi_debug use huge
amount memory.
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