Thread (2 messages) 2 messages, 2 authors, 2014-07-30

Re: [PATCH 1/2] alpha: Remove "strange" OSF/1 fork semantics

From: Richard Henderson <hidden>
Date: 2014-07-30 23:07:18
Also in: lkml

On 07/30/2014 12:04 PM, Måns Rullgård wrote:
Richard Henderson [off-list ref] writes:
quoted
The assignment to regs->r20 kills the original tls_val input
to the clone syscall, which means that clone can no longer be
restarted with the original inputs.

We could, perhaps, retain this result for true fork, but OSF/1
compatibility is no longer important.  Note that glibc has never
used the r20 result value, instead always testing r0 vs 0 to
determine the child/parent status.
What effect does this have on OSF/1 compat?
I don't know, as I've never had access to osf/1 myself.  It depends on how that
$20 value is used -- potentially, fork(3) no longer works.

I can imagine that we could retain these assignments under the condition of
clone_flags == 0, which both implies a basic fork as well as the fact that the
tls_val argument is unused.

But I do have to ask first if anyone actually cares.  Surely the amount of
osf-on-linux emulation is a vanishingly small proportion of the already small
alpha-linux population.


r~
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