Re: [Xen-devel] [PATCH 01/10] symbols: prefix static symbols with their source file name

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 21.10.15 at 10:43, <ian.campbell@xxxxxxxxxx> wrote:
> On Tue, 2015-10-20 at 04:38 -0600, Jan Beulich wrote:
>> This requires adjustments to the tool generating the symbol table and
>> its as well as nm's invocation.
>> 
>> Note: Not warning about duplicate symbols in the EFI case for now, as
>> a binutils bug causes misnamed file name entries to appear in EFI
>> binaries' symbol tables when the file name is longer than 18 chars.
>> (Not doing so also avoids other duplicates getting printed twice.)
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> ---
>> No changing ARM for now, as xSplice isn't targeted at it just yet.
> 
> The improved information from e.g. stack traces (which I'm supposing this
> also enables) seems valuable on ARM too. Is this something you plan to add
> or shall we ARM folks add it to our todo?

I can certainly implement it, but I can't - other than for x86 - verify
(other than by looking at the binary) that it has the intended effect.
(Of course all that hoping that I won't find more binutils issues in
the course of doing so.)

> I suspect the answer is no, but do you think there is much scope for making
> some of these complex linker runes common instead of arch specific?

I had considered this a while ago, but deemed it not worth it due
to the xen.efi rule necessarily being arch-specific (at least it would
be quite a bit harder to abstract this). But I guess we could move it
to xen/Rules.mk

> From what I can tell the actual arch change here is s/-n/-pa/ on the NM
> invocation (numeric sort => no sort + include debugger symbols) and then
> add --sysv --sort and optionally --want-dup to the tools/symbols
> invocation. Is it really as simple as that?

It is, luckily.

> Given we don't do a special EFI build/link I think on ARM we do want --warn
> -dup if at all possible.

Ultimately this is mostly useful for xSplice; when just considering stack
traces, a couple of duplicates don't really do much harm. But of course
using the same options for both architectures would simplify the making
common of the rule.

Jan


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