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From: "jack.chen" <zhunxun@gmail.com>
To: qemu <qemu-devel@nongnu.org>
Subject: [Qemu-devel] vhost-user question
Date: Wed, 31 Jan 2018 19:42:10 +0800	[thread overview]
Message-ID: <CADUDsAo6ku+WT1+DTG6u6CUjdg6xzG6LwBt8RwHK4eR_UWY=Jg@mail.gmail.com> (raw)

hello,I am confused when I read vhost-user source code in qemu.I know
vhost-user app shared memory with qemu by mmap,but why it can use fd which
is belong to qemu?
relative code:
 qemu code in function vhost_user_set_mem_table
fd = memory_region_get_fd(mr);
        if (fd > 0) {
            msg.payload.memory.regions[fd_num].userspace_addr =
reg->userspace_addr;
            msg.payload.memory.regions[fd_num].memory_size  =
reg->memory_size;
            msg.payload.memory.regions[fd_num].guest_phys_addr =
reg->guest_phys_addr;
            msg.payload.memory.regions[fd_num].mmap_offset = offset;
            assert(fd_num < VHOST_MEMORY_MAX_NREGIONS);
            fds[fd_num++] = fd;
        }

……
DPDK code in vhost_user_set_mem_table

mmap_addr = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE,
MAP_SHARED | MAP_POPULATE, fd, 0);
……

thanks a lot!

             reply	other threads:[~2018-01-31 11:42 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-31 11:42 jack.chen [this message]
2018-01-31 17:31 ` [Qemu-devel] vhost-user question Dr. David Alan Gilbert
2018-02-01  2:03   ` jack.chen
2018-02-01  9:51     ` Dr. David Alan Gilbert
2018-02-01 10:17       ` jack.chen
2018-02-01 10:30         ` Dr. David Alan Gilbert
2018-02-01 10:50           ` jack

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