Re: [dpdk-stable] [dpdk-dev] [PATCH dpdk-dev] rte_random: fix crash when random init

["Mattias Rönnblom" <mattias.ronnblom@ericsson.com>]

On 2020-04-14 06:43, Tonghao Zhang wrote:
> On Tue, Apr 14, 2020 at 12:07 PM Stephen Hemminger
> <stephen@networkplumber.org> wrote:
>> On Sun, 12 Apr 2020 16:27:53 +0800
>> xiangxia.m.yue@gmail.com wrote:
>>
>>> From: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>>>
>>> When rte_rand_init is invoked, and the kernel
>>> (kernel version < 3.17) running dpdk does't support
>>> *getentropy, at the same time, the cpu does't support
>>> rdseed, the rte_rand_init will invoke rte_get_timer_cycles
>>> which function will invoke rte_get_hpet_cycles
>>> (RTE_LIBEAL_USE_HPET was enabled) while *eal_hpet is not
>>> allocated.
>>>
>>> Fixes: faf8fd252785 ("eal: improve entropy for initial PRNG seed")
>>> Fixes: 3f002f069612 ("eal: replace libc-based random generation with LFSR")
>>>
>>> Cc: stable@dpdk.org
>>>
>>> Signed-off-by: Tonghao Zhang <xiangxia.m.yue@gmail.com>
>> Are you sure this patch won't change current default to use HPET (which is slower)?
> In rte_eal_timer_init (linux/eal_timer.c)， it will set
> eal_timer_source = EAL_TIMER_TSC too.
> So after rte_eal_init, eal_timer_source == EAL_TIMER_TSC which is the
> default timer source actually.
> Then this patch will affect RTE_INIT function which invoke
> rte_get_timer_cycles. but hpet is not available yet.


Would using rte_rdtsc() directly be an option?


>> Before this patch users would get TSC as default.
>
>