Re: [BUG] 4.9.0 build error on Alpha

From: Maciej W. Rozycki (macro@xxxxxxxxxxxxxx)
Date: Thu Jan 12 2017 - 07:52:39 EST


Bob,

> Credit to all who participated in working this issue. Matt -- attached
> is a patch set to be applied against the kernel.org 4.9.0 source tree.
> If it passes inspection, please approve and forward upstream.
>
> Apologies for not including in-line, but I don't trust my mailer to
> preserve formatting unless I send as an attachment.

Thanks for your contribution; you need to add a `Signed-off-by' tag
though for your change to go anywhere.

Also I think the <asm/uaccess.h> part will need some further work; at the
very least the comment needs to be updated to state why the conditional
has now been hardwired. Ultimately I think all the hackery can go and
`__copy_tofrom_user_nocheck' and `__clear_user' be replaced with direct
calls to `__copy_user' and `__do_clear_user' respectively (and
`__do_clear_user' renamed to `__clear_user' at the same time) as the +/-
4MiB branch range is too low these days to guarantee a kernel binary to
fit within.

Alternatively a configuration option might be added for the branch
optimisation to stay instead if selected, perhaps also adding the
`-msmall-text' compiler option to let small configurations take advantage
of it globally rather than just in <asm/uaccess.h>. This might not be
liked by people running build bots though as it would inevitably cause
some configurations to fail linking.

Maciej
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