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Re: [PATCH 1/2] documentation fixes #1


On Mon, Aug 30, 2010 at 1:51 AM, Gerald Pfeifer <gerald@pfeifer.com> wrote:
> On Tue, 17 Aug 2010, Andi Kleen wrote:
>> 2010-08-17 ?Andi Kleen ? ? ? ?<ak@linux.intel.com>
>>
>> ? ? ? * doc/install.texi (Building a native compiler): Remove
>> ? ? ? reference to broken BUILD_CONFIG=bootstrap-lto.
>> ? ? ? Document working method instead.
>> ---
>> ?gcc/doc/install.texi | ? 12 +++++++-----
>> ?1 files changed, 7 insertions(+), 5 deletions(-)
>>
>> diff --git a/gcc/doc/install.texi b/gcc/doc/install.texi
>> index fc9b988..c952edf 100644
>> --- a/gcc/doc/install.texi
>> +++ b/gcc/doc/install.texi
>> @@ -2108,6 +2108,13 @@ to work around this, by choosing @code{BOOT_CFLAGS} to avoid the parts
>> ?of the stage1 compiler that were miscompiled, or by using @samp{make
>> ?bootstrap4} to increase the number of stages of bootstrap.
>>
>> +You can also use @code{BOOT_CFLAGS} to force a LTO bootstrap with
>> +@samp{BOOTCFLAGS='-O2 -fwhopr=jobserver -fuse-linker-plugin -frandom-seed=1'}.
>
> BOOT_CFLAGS or BOOTCFLAGS?
>
> And "an LTO".
>
>> +Configure the compiler with @samp{--enable-stage1-languages=c,lto}. This
>> +will only work with the @command{gold} linker and if linker plugins are
>> +corrected configured. ?The @option{-frandom-seed=1} is needed to avoid
>> +bootstrap comparison failures.
>
> This sounds a bit tricky for our general user installation instructions;
> any chance to have all this triggered by a configure option or a simple
> "make bootstrap-lto" or just document it in pure developer documentation?
> (More a question to Diego et al, I guess.) ?Oh wait, that's what's there,
> but broken, right? :-(

The -frandom-seed requirement is indeed very unfortunate.  Andi - can't we
use sth based on a hash instead that would be stable across bootstrap?

Otherwise I'd like us to get rid of --enable-intermodule and its makefile
bits and simply fix --with-build-config=bootstrap-lto.

Richard.

>
> Gerald
>


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