Re: [kvm-unit-tests PATCH 3/3] x86: Support environments without test-devices

[Andrew Jones <drjones@redhat.com>]

On Fri, Jun 28, 2019 at 01:30:19PM -0700, Nadav Amit wrote:
> Enable to run the tests when test-device is not present (e.g.,
> bare-metal). Users can provide the number of CPUs and ram size through
> kernel parameters.

Can you provide multiboot a pointer to an initrd (text file) with
environment variables listed instead? Because this works

$ cat x86/params.c 
#include <libcflat.h>
int main(void)
{
    printf("nr_cpus=%ld\n", atol(getenv("NR_CPUS")));
    printf("memsize=%ld\n", atol(getenv("MEMSIZE")));
    return 0;
}

$ cat params.initrd 
NR_CPUS=2
MEMSIZE=256

$ qemu-system-x86_64 -nodefaults -device pc-testdev -device isa-debug-exit,iobase=0xf4,iosize=0x4 -vnc none -serial stdio -device pci-testdev -machine accel=kvm -kernel x86/params.flat -initrd params.initrd
enabling apic
enabling apic
nr_cpus=2
memsize=256


This works because setup_multiboot() looks for an initrd, and then,
if present, it gets interpreted as a list of environment variables
which become the unit tests **envp.

Thanks,
drew

> 
> On Ubuntu, for example, the tests can be run by copying a test to the
> boot directory (/boot) and adding a menuentry to grub (editing
> /etc/grub.d/40_custom):
> 
>   menuentry 'idt_test' {
> 	set root='ROOT'
> 	multiboot BOOT_RELATIVE/idt_test.flat ignore nb_cpus=48 \
> 		ram_size=4294967296 no-test-device
>   }
> 
> Replace ROOT with `grub-probe --target=bios_hints /boot` and
> BOOT_RELATIVE with `grub-mkrelpath /boot`, and run update-grub.
> 
> Note that the first kernel parameter is ignored for compatibility with
> test executions through QEMU.
>