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SubjectRe: [4/6] Xen VMM #4: HAS_ARCH_DEV_MEM
On Wed, Dec 08, 2004 at 07:30:31AM +0000, Ian Pratt wrote:
>
> This patch adds ARCH_HAS_DEV_MEM, enabling per-architecture
> implementations of /dev/mem and thus avoids a number of messy
> #ifdef's. Although the mmap case can be solved easily be simply using
> io_remap_page_range instead of remap_pfn_range on all architecutres,
> we need to support read/write of /dev/mem in order for dmidecode etc
> to work. These changes are more messy, and we believe warrant making
> /dev/mem arch specific, which also cleans up uncached_access too.
>
> Signed-off-by: ian.pratt@cl.cam.ac.uk
>
> ---
>
>
> diff -Nurp pristine-linux-2.6.10-rc3/drivers/char/mem.c tmp-linux-2.6.10-rc3-xen.patch/drivers/char/mem.c
> --- pristine-linux-2.6.10-rc3/drivers/char/mem.c 2004-12-03 21:53:47.000000000 +0000
> +++ tmp-linux-2.6.10-rc3-xen.patch/drivers/char/mem.c 2004-12-08 00:52:40.000000000 +0000
> @@ -143,7 +143,7 @@ static ssize_t do_write_mem(void *p, uns
> return written;
> }
>
> -
> +#ifndef ARCH_HAS_DEV_MEM
> /*
> * This funcion reads the *physical* memory. The f_pos points directly to the
> * memory location.
> @@ -189,8 +189,9 @@ static ssize_t write_mem(struct file * f
> return -EFAULT;
> return do_write_mem(__va(p), p, buf, count, ppos);
> }
> +#endif
>
> -static int mmap_mem(struct file * file, struct vm_area_struct * vma)
> +static int mmap_kmem(struct file * file, struct vm_area_struct * vma)
> {
> #ifdef pgprot_noncached
> unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
> @@ -567,7 +568,7 @@ static int open_port(struct inode * inod
> return capable(CAP_SYS_RAWIO) ? 0 : -EPERM;
> }
>
> -#define mmap_kmem mmap_mem
> +#define mmap_mem mmap_kmem
> #define zero_lseek null_lseek
> #define full_lseek null_lseek
> #define write_zero write_null
> @@ -575,6 +576,7 @@ static int open_port(struct inode * inod
> #define open_mem open_port
> #define open_kmem open_mem
>
> +#ifndef ARCH_HAS_DEV_MEM
> static struct file_operations mem_fops = {
> .llseek = memory_lseek,
> .read = read_mem,
> @@ -582,6 +584,9 @@ static struct file_operations mem_fops =
> .mmap = mmap_mem,
> .open = open_mem,
> };
> +#else
> +extern struct file_operations mem_fops;
> +#endif

Any chance you could put the /dev/mem implementation into a separate
file, ala drivers/char/devmem.c and avoid the ifdefs? ARCH_HAS_DEV_MEM
would have to become a CONFIG option then

-
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