[doc/tracepoint] Change *$esp@300 to *(unsigned char *)$esp@300.

[doc/tracepoint] Change *$esp@300 to *(unsigned char *)$esp@300.

[Hui Zhu]

Hi,

I found that if want collect stack in tracepoint action like doc said
will got error.

collect $rsp@512
Left operand of `@' must be an object in memory.

But change to:
collect *(unsigned char *)$rsp@512

Will fix it.

So I make a patch for doc.

Please help me review it.

Thanks,
Hui

2011-09-16  Hui Zhu  <teawater@gmail.com>

	* gdb.texinfo (Tracepoint Restrictions): Change *$esp@300
	to *(unsigned char *)$esp@300.
---
 doc/gdb.texinfo |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/doc/gdb.texinfo
+++ b/doc/gdb.texinfo
@@ -10627,7 +10627,7 @@ by @code{ptr}.
 @item
 It is not possible to collect a complete stack backtrace at a
 tracepoint.  Instead, you may collect the registers and a few hundred
-bytes from the stack pointer with something like @code{*$esp@@300}
+bytes from the stack pointer with something like @code{*(unsigned
char *)$esp@@300}
 (adjust to use the name of the actual stack pointer register on your
 target architecture, and the amount of stack you wish to capture).
 Then the @code{backtrace} command will show a partial backtrace when

Re: [doc/tracepoint] Change *$esp@300 to *(unsigned char *)$esp@300.

[Eli Zaretskii]

> From: Hui Zhu <teawater@gmail.com>
> Date: Fri, 16 Sep 2011 15:54:54 +0800
> Cc: Eli Zaretskii <eliz@gnu.org>
> 
> 2011-09-16  Hui Zhu  <teawater@gmail.com>
> 
> 	* gdb.texinfo (Tracepoint Restrictions): Change *$esp@300
> 	to *(unsigned char *)$esp@300.

OK.

Re: [doc/tracepoint] Change *$esp@300 to *(unsigned char *)$esp@300.

[Hui Zhu]

Thanks Eli.

Checked in.

http://sourceware.org/cgi-bin/cvsweb.cgi/src/gdb/doc/gdb.texinfo.diff?cvsroot=src&r1=1.861&r2=1.862

Best,
Hui

On Fri, Sep 16, 2011 at 16:13, Eli Zaretskii <eliz@gnu.org> wrote:
>> From: Hui Zhu <teawater@gmail.com>
>> Date: Fri, 16 Sep 2011 15:54:54 +0800
>> Cc: Eli Zaretskii <eliz@gnu.org>
>>
>> 2011-09-16  Hui Zhu  <teawater@gmail.com>
>>
>>       * gdb.texinfo (Tracepoint Restrictions): Change *$esp@300
>>       to *(unsigned char *)$esp@300.
>
> OK.
>

Re: [doc/tracepoint] Change *$esp@300 to *(unsigned char *)$esp@300.

[Pedro Alves]

On Friday 16 September 2011 08:54:54, Hui Zhu wrote:
> I found that if want collect stack in tracepoint action like doc said
> will got error.
> 
> collect $rsp@512
> Left operand of `@' must be an object in memory.

The manual actually says: "something like *$esp@300",
which indeed doesn't work nowadays:

(gdb) maint agent *$rsp@300
Attempt to dereference a generic pointer.

(it's not a bug, it was made to error on purpose)

In any case, the patch is a good change, thanks!

-- 
Pedro Alves