svn commit: r238668 - head/sys/amd64/amd64
Bruce Evans
brde at optusnet.com.au
Sat Jul 21 13:29:20 UTC 2012
On Sat, 21 Jul 2012, Konstantin Belousov wrote:
> Log:
> Stop clearing x87 exceptions in the #MF handler on amd64. If user code
> understands FPU hardware enough to catch SIGFPE and unmask exceptions
> in control word, then it may as well properly handle return from
> SIGFPE without causing an infinite loop of #MF exceptions due to
> faulting instruction restart, when needed.
>
> Clearing exceptions causes information loss for handlers which do
> understand FPU hardware, and struct siginfo si_code member cannot be
> considered adequate replacement for en_sw content due to translation.
>
> Supposed reason for clearing the exceptions, which is IRQ13 handling
> oddities, were never applicable to amd64.
>
> Note: this change will be merged to i386 kernel as well, since we do
> not support IRQ13 delivery of #MF notifications for some time.
>
> Requested by: bde
> MFC after: 1 week
Thanks.
The comment formatting has lost its constent 2-space sentence breaks.
Bruce
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