Re: [Qemu-devel] [PATCH 1/6] qtest: add test framework

[Anthony Liguori]

On 01/16/2012 10:59 AM, Stefan Hajnoczi wrote:
> On Fri, Jan 13, 2012 at 6:32 PM, Anthony Liguori<address@hidden>  wrote:
> > +    if (strcmp(words[0], "outb") == 0 ||
> > +        strcmp(words[0], "outw") == 0 ||
> > +        strcmp(words[0], "outl") == 0) {
> > +        uint16_t addr;
> > +        uint32_t value;
> > +
> > +        g_assert(words[1]&&  words[2]);
> > +        addr = strtol(words[1], NULL, 0);
> > +        value = strtol(words[2], NULL, 0);
> > +
> > +        if (words[0][3] == 'b') {
> > +            cpu_outb(addr, value);
> > +        } else if (words[0][3] == 'w') {
> > +            cpu_outw(addr, value);
> > +        } else if (words[0][3] == 'l') {
> > +            cpu_outl(addr, value);
> > +        }
> > +        qtest_send_prefix(chr);
> > +        qtest_send(chr, "OK\n");
> > +    } else if (strcmp(words[0], "inb") == 0 ||
> > +        strcmp(words[0], "inw") == 0 ||
> > +        strcmp(words[0], "inl") == 0) {
> > +        uint16_t addr;
> > +        uint32_t value = -1U;
> > +
> > +        g_assert(words[1]);
> > +        addr = strtol(words[1], NULL, 0);
> > +
> > +        if (words[0][2] == 'b') {
> > +            value = cpu_inb(addr);
> > +        } else if (words[0][2] == 'w') {
> > +            value = cpu_inw(addr);
> > +        } else if (words[0][2] == 'l') {
> > +            value = cpu_inl(addr);
> > +        }
> > +        qtest_send_prefix(chr);
> > +        qtest_send(chr, "OK 0x%04x\n", value);
>
> Endianness is a little weird here.  memory.c will byteswap if target
> and device endianness differ.
>
> Imagine the case where we're on an x86 host, running a ppc guest,
> reading from PCI configuration space (little-endian).

These functions expect to get host native endian.  The qtest wire protocol is a 
string (which has no endianness) and converts it to host native endian.

>  Since ppc
> (target endian) is big-endian and the device is little-endian the
> value read/written will be byteswapped.  However, our qtest runs on
> the host and therefore we don't want that automatic swap (or we need
> to neutralize it by performing another byteswap on top).

ppc wouldn't use outb/inb.  It would do mmio to the PIO region which would send 
it through the host controller (which would do byte swapping as necessary).

So a qtest test case would have to do little endian MMIO to interact with the 
PCI bus.

Regards,

Anthony Liguori

> Stefan