On Wed, 2007-12-05 at 11:17 -0500, David H. Lynch Jr. wrote:
> This might be slightly OT here, but would anyone know where there
> might be a reference that indicates at precisely what version a given
> symbol either appeared or disappeared within the Linux kernel ?
>
> As an example if a driver is supposed to work for 2.6 and 2.4 and
> uses sysfs, or cdev, or alloc_chr_dev_region or ...
> How can one tell at what point that api or symbol appeared so that
> the proper conditionals appear within the driver.
>
> The last one that bit me was I made a collection of casting changes
> to address 64bit vs. 32bit targets, and found that using the C99 fixed
> size types - uint32_t, ... made life much more pleasant, after putting
> them I nobody else could build because uintptr_t did not appear until
> 2.6.24, and I still have not figured out exactly when uint32_t etc.
> appeared.
I believe the standard C99 types like uint32_t have been there for ever,
basically. Maybe not in Linux 1.0, but as far back as anyone might ever
sensibly care.
That doesn't include uintptr_t though. For that we usually use 'unsigned
long'. If ever there is an architecture where 'unsigned long' isn't big
enough for a pointer, Linux is going to break :)
> I would think there ought to be some resource besides group memory
> to look this up ?
> Is there a way to use git to look back through the history of a
> symbol rather than a file.
pmac /pmac/git/libertas-2.6 $ git-annotate include/linux/types.h | grep
uintptr_t
142956af ( Al Viro 2007-10-29 05:11:28 +0000 40)typedef
unsigned long uintptr_t;
pmac /pmac/git/libertas-2.6 $ git-show 142956af
commit 142956af525002c5378e7d91d81a01189841a785
Author: Al Viro <[EMAIL PROTECTED]>
Date: Mon Oct 29 05:11:28 2007 +0000
fix abuses of ptrdiff_t
Use of ptrdiff_t in places like
- if (!access_ok(VERIFY_WRITE, u_tmp->rx_buf,
u_tmp->len))
+ if (!access_ok(VERIFY_WRITE, (u8 __user *)
+ (ptrdiff_t) u_tmp->rx_buf,
+ u_tmp->len))
is wrong; for one thing, it's a bad C (it's what uintptr_t is for; in
general
we are not even promised that ptrdiff_t is large enough to hold a pointer,
just enough to hold a difference between two pointers within the same
object).
For another, it confuses the fsck out of sparse.
Use unsigned long or uintptr_t instead. There are several places misusing
ptrdiff_t; fixed.
Signed-off-by: Al Viro <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
--
dwmw2
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