IRC, freenode, #hurd, 2013-05-10
<braunr> what code have you used if any (or is it your own implementation)
<youpi> I ended up writing my own implementation
<braunr> eh :)
<youpi> the libahci/ahci code from linux is full of linux-specific stuff
<youpi> it would mean working on gluing that
<youpi> which woudl rather be just done in block-dde
<youpi> I was told at fosdem that ahci is not actually very difficult
<youpi> and it isn't indeed
<braunr> that's why i usually encourage to use netbsd code
<braunr> any chance using ahci might speed up our virtual machines ?
<youpi> they are already using DMA, so probably no
<youpi> (with the driver I've pushed)
<youpi> adding support for tagged requests would permit to submit several
requests at a time
<youpi> _that_ could improve it
<youpi> (it would make it quite more complex too)
<youpi> but not so much actually
<anatoly> What about virtio? will it speed up?
<youpi> probably not so much
<youpi> because in the end it works the same
<youpi> the guest writes the physical addresse in mapped memory
<youpi> kvm performs the read into th epointed memory, triggers an irq
<youpi> the guest takes the irq, marks as done, starts the next request,
<youpi> most enhancements that virtio could bring can already be achieved
<youpi> one can probably go further with virtio, but doing it with ahci
will also benefit bare hardware
<youpi> anatoly: aka SATA
<anatoly> some sort of general protocol to work with any SATA drive via
AHCI-compatible host controller?
<youpi> braunr: I may be mistaken, but it does seem ahci is faster than ide
<youpi> possibly because the ide driver is full of hardcoded wait loops
<braunr> interesting :)
<youpi> usleeps here and there
<braunr> oh right
<braunr> i wonder how they're actually implemented
<youpi> so it would make sense to use that on shattrath
<youpi> a nasty buggy busy-loop
<braunr> yes but ending when ?
<youpi> when a given number of loops have elapsed
<youpi> that's where "buggy" applies :)
<braunr> ok so buggy implies the loop isn't correctly calibrated
<youpi> it isn't calibrated at all actually
<youpi> it was probably calibrated on some 486 or pentium hardware :)
<braunr> yeah that's what i imagined too
<braunr> we'll need some measurements but if it's actually true, it's even
IRC, freenode, #hurd, 2013-05-11
<youpi> ah, also, worth mentioning: the AHCI driver supports up to 2TiB
<youpi> (as opposed to our IDE driver which supports only LBA28, 128GiB)
<youpi> supporting more than 2TiB would require an RPC change, or using
<youpi> (which wouldn't be a bad idea anyway)
<braunr> i think we should switch to uint64_t addressable vm_objects
<braunr> which would allow to support large files too
<youpi> braunr: yep
IRC, freenode, #hurd, 2013-05-13
<braunr> the hurd, running on vbox, with a sata controler :)
<braunr> hum, problem with an extended partition
<anatoly_> qemu/kbm doesn't have sata controller, am I right?
<braunr> anatoly: recent versions might
<anatoly> braunr: found first link, too. Thanx for the second one
<braunr> looks ok in recent versions
<braunr> looks useful to have virtio drivers though
<anatoly> virtio is shown as fastest way for IO in the presentation
<anatoly> Hm, failed to run qemu with AHCI enabled
<anatoly> qemu 1.1 from debian testing
<anatoly> youpi how do run qemu with AHCI enabled?
IRC, freenode, #hurd, 2013-05-14
<anatoly> can somebody ask youpi how he runs qemu with AHCI please?
<gnu_srs> I think he used vbox? Did not find any AHCI option for kvm
<anatoly> gnu_srs: http://wiki.qemu.org/ChangeLog/0.14#IDE_.2F_AHCI
<anatoly> but it doesn't work for me the same version of kvm
<braunr_> anatoly: have you checked how the debian package builds it ?
<anatoly> braunr: mach sees AHCI device
<braunr> oh :)
<anatoly> the problem is in last option "-device
<anatoly> lvm says 'invalid option'
<braunr> anatoly: can you give more details please ?
<braunr> lvm ?
<braunr> i don't understand
<braunr> how can mach probe an ahci drive if you can't start kvm ?
<anatoly> I ran it without last option
<braunr> then why do you want that option ?
<anatoly> But, actually I entered command with mistake. I retried it and it
works. But got "start ext2fs: ext2fs: device:hd0s2: No such device or
<anatoly> Sorry for confusing
<braunr> that's normal
<braunr> it should be sd0s2
<bddebian2> Right because the device names are different
<braunr> be aware that gnumach couln't see my extended partitions when i
tried that yesterday
<braunr> i don't know what causes the problem
<anatoly> Yeah, I understand, I just note about it to show that it works
<anatoly> And I was wring
<braunr> is that the version in wheezy ?
<anatoly> I'm using testing, but it's same
<braunr> the sceen.net VMs will soon use that then
<anatoly> I don't have extended partions
<anatoly> Booted with AHCI! :-)
<anatoly> It freezes while downloading packages for build-essential
fake-root dependencies with AHCI enabled
<youpi> anatoly: is the IRQ of the ahci controller the same as for your
ethernet device? (you can see that in lspci -v)
<anatoly> youpi: will check
<anatoly> youpi both uses IRQ 111
<youpi> anatoly: ok, that might be why
<youpi> is this kvm?
<youpi> if so, you can set up a second ahci controler
<youpi> and attach devices to it
<youpi> so the irq is not the same
<youpi> basically, the issue is about dde disabling the irq
<youpi> during interrupt handler
<youpi> which conflicts with ahci driver needs
IRC, freenode, #hurd, 2013-05-15
<anatoly> youpi: yes, it's kvm. Will try a second ahci controller
<Slex> I read recentrly was added ahci driver, is it in userland or
<gnu_srs> kernel-land the change was in gnumach
IRC, freenode, #hurd, 2013-05-18
<youpi> about the IRQ conflict, it's simply that both dde and the ahci
driver need to disable it
<youpi> it needs to be coherent somehow
IRC, freenode, #hurd, 2013-05-20
<anatoly> gnu_srs: kvm -m 1G -drive
ahci,id=ahci-1 -device ahci,id=ahci-2 -device
<anatoly> who knows what does "ich9-ahci.multifunction=on/off" parameter
for kvm's ahci device mean?
<anatoly> well, I was a bit incorrect :-) The options is relative to PCI
<anatoly> s/options is relative/options relates
IRC, freenode, #hurd, 2013-05-24
<anatoly> I don't see freezes anymore while downloading packages with AHCI
<youpi> anatoly: by fixing the shared IRQ ?
<anatoly> youpi: yes, I added second AHCI as you suggested
<youpi> so it's probably the shared IRQ issue
<anatoly> NIC and AHCI have similar IRQ when only one AHCI is enabled
<anatoly> according lspci output
IRC, freenode, #hurd, 2013-06-18
<braunr> youpi: is there a simple way from hurd to check interrupts ?
<youpi> what do you mean by "check interrupts" ?
<braunr> if they're shared
<youpi> I still don't understand :)
<braunr> i'm setting up sata
<youpi> ah, knowing the number
<youpi> you can read that from lspci -v
<braunr> i get set root='hd-49,msdos1' in grub.cfg when changing the
device.map file to point to sd0
<braunr> i wonder if it's necessary
<braunr> i guess i just have to tell gnumach to look for sd0, not grub
<braunr> youpi: the trick you mentioned was to add another controler, right
<braunr> youpi: looks fine :)
<braunr> and yes, i left hd0 in grub's device.map
<braunr> although i have lots of errors on hd0s6 (/home)
<braunr> youpi: there must be a bug with large sizes
<braunr> i'll stick with ide for now, but at least setting sata with
libvirt was quite easy to do
<braunr> so we can easily switch later