Michael Matz <m...@suse.de> writes: > Hi, > > On Tue, 25 Feb 2014, Peter Maydell wrote: > >> On 25 February 2014 13:33, Michael Matz <m...@suse.de> wrote >> > The biggest road-block is that signal vs syscall handling is >> > fundamentally broken in linux-user and it's unfixable without >> > assembler implementations of the syscall caller. >> >> I'm not entirely sure it's possible to fix even with >> hand-rolled assembly, to be honest. > > I am fairly sure. The problem is "simply" to detect if the signal arrived > while inside the kernel (doing the syscalls job) or still or already > outside. This structure helps with that: <snip>
Is this "simply" a case of having a precise state in/around syscalls? AIUI we already have such a mechanism for dealing with faults in translated code so this is all aimed at when an asynchronous signal arrives somewhere in QEMU's own code. So this case be: * the execution/translation loop * a helper function * a syscall (helper jump out of execution/translation loop?) I wonder if it would be possible to defer the handing of the signal back to the process until we know we are precise? -- Alex Bennée Finding this all eerily familiar.
