Re: The meaning of acronym of PIO in kernel?
Hello, On Fri, Nov 4, 2011 at 8:58 AM, loody milo...@gmail.com wrote: Hi all: I found except DMA transfer, there is a mode called PIO. Where I can find the document of this and what is full name of it? Use search engine powers on PIO, for Programmed Input/Output. It's not Linux specific, it's computer / micro-architecture specific terminology. Regards, -- Leon ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to refer to the unamed structure in page struct
Hi Jimmy,
On Fri, Nov 4, 2011 at 8:27 AM, Jimmy Pan dsp...@gmail.com wrote:
truct page {
unsigned long flags; /* Atomic flags, some possibly
* updated asynchronously */
atomic_t _count; /* Usage count, see below. */
union {
atomic_t _mapcount; /* Count of ptes mapped in mms,
* to show when page is mapped
* limit reverse map searches.
*/
struct { /* SLUB */
u16 inuse;
u16 objects;
};
};
union {
struct {
unsigned long private; /* Mapping-private opaque data:
* usually used for
buffer_heads
* if PagePrivate set; used for
* swp_entry_t if
PageSwapCache;
* indicates order in the buddy
* system if PG_buddy is set.
*/
struct address_space *mapping; /* If low bit clear, points to
* inode address_space, or
NULL.
* If page mapped as anonymous
* memory, low bit is set, and
* it points to anon_vma
object:
* see PAGE_MAPPING_ANON below.
*/
};
#if USE_SPLIT_PTLOCKS
spinlock_t ptl;
#endif
struct kmem_cache *slab; /* SLUB: Pointer to slab */
struct page *first_page; /* Compound tail pages */
};
You just reference the variable as if the unnamed union weren't there
(i.e. just like unnamed unions in C++).
Here's an example from the kernel source tree:
http://lxr.linux.no/linux+v3.1/include/linux/mm.h#L419
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
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Re: How to refer to the unamed structure in page struct
On Sat, Nov 5, 2011 at 12:00 AM, Dave Hylands dhyla...@gmail.com wrote:
Hi Jimmy,
On Fri, Nov 4, 2011 at 8:27 AM, Jimmy Pan dsp...@gmail.com wrote:
truct page {
unsigned long flags; /* Atomic flags, some possibly
* updated asynchronously */
atomic_t _count; /* Usage count, see below. */
union {
atomic_t _mapcount; /* Count of ptes mapped in mms,
* to show when page is mapped
* limit reverse map searches.
*/
struct { /* SLUB */
u16 inuse;
u16 objects;
};
};
union {
struct {
unsigned long private; /* Mapping-private opaque
data:
* usually used for
buffer_heads
* if PagePrivate set; used
for
* swp_entry_t if
PageSwapCache;
* indicates order in the
buddy
* system if PG_buddy is set.
*/
struct address_space *mapping; /* If low bit clear, points to
* inode address_space, or
NULL.
* If page mapped as anonymous
* memory, low bit is set, and
* it points to anon_vma
object:
* see PAGE_MAPPING_ANON
below.
*/
};
#if USE_SPLIT_PTLOCKS
spinlock_t ptl;
#endif
struct kmem_cache *slab; /* SLUB: Pointer to slab */
struct page *first_page; /* Compound tail pages */
};
You just reference the variable as if the unnamed union weren't there
(i.e. just like unnamed unions in C++).
Here's an example from the kernel source tree:
http://lxr.linux.no/linux+v3.1/include/linux/mm.h#L419
--
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
Well, I see, but what is the use of the union and structure?
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