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Re: [RFC] Enable GDB handle compressed target.xml returned by GDB stub
- From: Jonathan Larmour <jifl at eCosCentric dot com>
- To: Terry Guo <terry dot guo at arm dot com>
- Cc: Pedro Alves <palves at redhat dot com>, Ulrich Weigand <uweigand at de dot ibm dot com>, Yao Qi <yao at codesourcery dot com>, gdb-patches at sourceware dot org, tromey at redhat dot com, Richard Earnshaw <Richard dot Earnshaw at arm dot com>, Joey Ye <Joey dot Ye at arm dot com>
- Date: Fri, 22 Jun 2012 18:19:26 +0100
- Subject: Re: [RFC] Enable GDB handle compressed target.xml returned by GDB stub
- References: <201206131312.q5DDCUfK028160@d06av02.portsmouth.uk.ibm.com> <4FD9B96C.9020908@redhat.com> <4FDA0543.9030100@eCosCentric.com> <000101cd4dee$db02a030$9107e090$@guo@arm.com>
On 19/06/12 08:40, Terry Guo wrote:
> Jifl wrote:
>> 1) Remote stub can return compressedXML+ in qSupported response
>>
>> 2) The current syntax of qXfer:features:read is:
>> qXfer:features:read:ANNEX:OFFSET,LENGTH I suggest instead:
>> qXfer:features:read:ANNEX:OFFSET,LENGTH[,Z] where the ,Z is only
>> attempted if the stub supports the compressedXML remote protocol
>> feature.
>
> I don't think it will work after I looked into some open source GDB
> servers like STLINk, OpenOCD. After they confirm that the packet is
> qXfer:features:read, they just extract information of ANNEX, OFFSET and
> LENGTH. Whether there is a "Z" doesn't impact their response behavior.
Then they wouldn't have sent compressedXML+ in their qSupported response.
So they'll continue to work fine.
> But the new "zread" can work because those existing gdb servers do
> check whether the op is "read". So for "zread", that check will fail
> and an error code will be returned to host gdb, thus host gdb knows the
> compressed xml file isn't supported. While for the new stub that knows
> "zread", the compressed xml file will be returned.
Sure, but with my suggestion we save having to implement a new command on
the remote side, as well as avoiding a round trip of attempting the zread,
failing, and fallback to read every time.
Jifl
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