Hello,
On Mon, 21 Nov 2022, Bernhard Beschow wrote:
Am 21. November 2022 22:43:50 UTC schrieb "Philippe Mathieu-Daudé"
<phi...@linaro.org>:
On 21/11/22 16:34, Bernhard Beschow wrote:
Am 27. Oktober 2022 20:47:19 UTC schrieb "Philippe Mathieu-Daudé"
<phi...@linaro.org>:
Linux kernel expects the northbridge & southbridge chipsets
configured by the BIOS firmware. We emulate that by writing
a tiny bootloader code in write_bootloader().
Upon introduction in commit 5c2b87e34d ("PIIX4 support"),
the PIIX4 configuration space included values specific to
the Malta board.
Set the Malta-specific IRQ routing values in the embedded
bootloader, so the next commit can remove the Malta specific
bits from the PIIX4 PCI-ISA bridge and make it generic
(matching the real hardware).
Signed-off-by: Philippe Mathieu-Daudé <phi...@linaro.org>
---
FIXME: Missing the nanoMIPS counter-part!
Who will be taking care of this? I have absolutely no clue how the
write_bootloader functions work, so I don't see how to fix it.
Oh actually I wrote that and tested it but context switched and forgot
about it... I'll look back when I get some time, probably around the
release.
Unrelated to this but found it while looking at malta.c now: another
possible clean up is to replace the local generate_eeprom_spd() func with
spd_data_generate() from hw/i2c/smbus_eeprom.c that other boards use
already but I did not change malta because I could not test it. If you can
test malta then it should be an easy change and simplify malta.c a bit.
Couldn't we just do it like in pegasos2_init() where the registers are
initialized by QEMU directly if there is no bootloader binary configured? I
could do that.
I rather mimic bootloaders... maybe a matter of taste?
Is that a bootloader or a replacement firmware? To me bootloader is some
OS specific binary that is loaded by firware to boot an OS. But there are
OS independent bootloaders like grub so maybe you could emulate something
like that, I don't know what malta does.
If there's no firmware binary QEMU should provide something to replace it
to give the expected environment for the binary loaded by -kernel. In case
of pegasos2 the init method sets up regs to init devices as done by the
firmware and the rest is implemented by VOF (loaded from pc-bios) that
provices the OpenFirmware client interface. The device setup in init is
needed because VOF does not do that.
I don't mind either way. I meant that I could help with the second
approach but not with the current one since I have no clue whatsoever
how it works. There are just too many magic constants that don't make
any sense to me, and too many layers of indirection, for example.
If malta has a replacement firmware for this case maybe it could be stored
in a binary in pc-bios and loaded from there instead of writing it in hex
to guest memory. That binary could even be assembled from source which
should make it simpler to write and change. Or is YAMON open source?
According to this page it is:
https://www.mips.com/develop/tools/boot-loaders/ so maybe it could be
included as a firmware binary instead of being emulated?
Regards,
BALATON Zoltan
Anyway, I'm asking for the current state because I'm pretty much ready for
posting a v3 of my PIIX consolidation series which now depends on this series.
Best regards,
Bernhard
Regards,
Phil.
