On 1/9/2019 11:53 AM, Boris Ostrovsky wrote:
On 1/9/19 6:53 AM, Stefano Garzarella wrote:
Hi Liam,
On Tue, Jan 8, 2019 at 3:47 PM Liam Merwick <liam.merw...@oracle.com> wrote:
QEMU sets the hvm_modlist_entry in load_linux() after the call to
load_elfboot() and then qboot loads it in boot_pvh_from_fw_cfg()
But the current PVH patches don't handle initrd (they have
start_info.nr_modules == 1).
Looking in the linux kernel (arch/x86/platform/pvh/enlighten.c) I saw:
/* The first module is always ramdisk. */
if (pvh_start_info.nr_modules) {
struct hvm_modlist_entry *modaddr =
__va(pvh_start_info.modlist_paddr);
pvh_bootparams.hdr.ramdisk_image = modaddr->paddr;
pvh_bootparams.hdr.ramdisk_size = modaddr->size;
}
So, putting start_info.nr_modules = 1, means that the first
hvm_modlist_entry should have the ramdisk paddr and size. Is it
correct?
That's my understanding.
I think what's missing, is that we just need Qemu or qboot/seabios to
properly populate the pvh_start_info.modlist_paddr with the address (as
usable by the guest) of the hvm_modlist_entry which correctly defines
the details of the initrd that has already been loaded into memory that
is accessible by the guest.
-Maran
During (or after) the call to load_elfboot() it looks like we'd need to
do something like what load_multiboot() does below (along with the
associated initialisation)
400 fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, ADDR_MBI);
401 fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, sizeof(bootinfo));
402 fw_cfg_add_bytes(fw_cfg, FW_CFG_INITRD_DATA, mb_bootinfo_data,
403 sizeof(bootinfo));
In this case I think they used the FW_CFG_INITRD_* to pass bootinfo
varibales to the guest, maybe we could add something like what
linux_load() does:
/* load initrd */
if (initrd_filename) {
...
initrd_addr = (initrd_max-initrd_size) & ~4095;
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_ADDR, initrd_addr);
fw_cfg_add_i32(fw_cfg, FW_CFG_INITRD_SIZE, initrd_size);
fw_cfg_add_bytes(fw_cfg, FW_CFG_INITRD_DATA, initrd_data, initrd_size);
...
}
Then we can load the initrd in qboot or in the optionrom that I'm writing.
What do you think?
Why not specify this in pvh_start_info? This will be much faster for
everyone, no need to go through fw_cfg.
-boris
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