共享内存最多1G？

今天同事问了这个问题，共享内存最多只能设成1G？之前只记得可以通过/proc/sys/kernel/shmmax来进行修改，但是最大是多少，倒是没有进行深究。

1G的来由主要来自man proc：
/proc/sys/kernel/shmmax
This? file? can? be? used to query and set the run time limit on the maximum (System V IPC) shared memory segment size that can be created. Shared memory segments up to 1GB are now supported in the kernel.? This value defaults to SHMMAX.

/proc/sys/kernel/shmall<br……>