Re: [Qemu-devel] [PATCH 1/2] target/arm: Use extract2 for EXTR

[Richard Henderson]

On 7/9/19 6:40 PM, Peter Maydell wrote:
> On Tue, 14 May 2019 at 02:11, Richard Henderson
> <address@hidden> wrote:
>>
>> This is, after all, how we implement extract2 in tcg/aarch64.
>>
>> Reviewed-by: Peter Maydell <address@hidden>
>> Signed-off-by: Richard Henderson <address@hidden>
>> ---
>>  target/arm/translate-a64.c | 38 ++++++++++++++++++++------------------
>>  1 file changed, 20 insertions(+), 18 deletions(-)
> 
> It turns out that we have a regression in booting at least
> some Linux kernels with TCG on aarch64 hosts (the same
> config works fine on x86-64 hosts). Git bisect points to
> this commit (80ac954c369e7e61bd1ed0) as the cause...

Bisect would finger that one, since this second commit is the only method by
which an extract2 operation would be emitted by the aarch64 target + aarch64
host combination.

(The other place that extract2 might be used are deposits, but aarch64 host has
all of those covered with the bfi instruction.)

Fix for tcg/aarch64 coming up...


r~