On Sun, 13 Oct 2013 19:33:19 +0200 Igor Mammedov <imamm...@redhat.com> wrote:
> On Sun, 13 Oct 2013 19:46:09 +0300 > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > On Sun, Oct 13, 2013 at 06:23:28PM +0200, Igor Mammedov wrote: > > > On Sun, 13 Oct 2013 18:59:20 +0300 > > > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > > > > On Sun, Oct 13, 2013 at 05:11:54PM +0200, Igor Mammedov wrote: > > > > > On Sun, 13 Oct 2013 15:31:23 +0300 > > > > > "Michael S. Tsirkin" <m...@redhat.com> wrote: > > > > > > > > > > > On Sun, Oct 13, 2013 at 02:13:44PM +0200, Igor Mammedov wrote: > > > > > > > Currently 64-bit PCI BARs are unconditionally mapped by BIOS right > > > > > > > over 4G + RamSizeOver4G location, which doesn't allow to reserve > > > > > > > extra space before 64-bit PCI window. For memory hotplug an extra > > > > > > > RAM space might be reserved after present 64-bit RAM end and BIOS > > > > > > > should map 64-bit PCI BARs after it. > > > > > > > > > > > > > > Introduce "etc/pcimem64-start" romfile to provide BIOS a hint > > > > > > > where it should start mapping of 64-bit PCI BARs. If romfile is > > > > > > > missing, BIOS reverts to legacy behavior and starts mapping right > > > > > > > after high memory. > > > > > > > > > > > > > > Signed-off-by: Igor Mammedov <imamm...@redhat.com> > > > > > > > --- > > > > > > > v2: > > > > > > > * place 64-bit window behind high RAM end if > > > > > > > "etc/pcimem64-start" > > > > > > > points below it. > > > > > > > > > > > > Hmm I had an alternative suggestion of passing smbios > > > > > > tables in from QEMU (seabios already has a mechanism for this). > > > > > > We could then simply increase the existing RamSize variable. > > > > > > > > > > > > What do you think about this idea? > > > > > There is several issues with RamSizeOver4G I see: > > > > > 1. As Gerd pointed out it is also used to setup a part of e820 tables. > > > > > It possibly could be also changed see "[Qemu-devel] [RfC PATCH] > > > > > e820: pass > > > > > high memory too" but it will be more complicated to keep seabios > > > > > backward/forward compatible if we use RamSizeOver4G for passing. > > > > > > > > What are the compatibility worries, exactly? > > > > > > > > The way I see it, if QEMU wants to be compatible it can't > > > > use memory hotplug. In that case RamSizeOver4G will have > > > > the old meaning which should work without issues. > > > QEMU can't know what BIOS version is used and error out in wrong case, > > > and that > > > could cause hard to guess what going wrong bugs in the guest. > > > > > > > > > > > > 2. It doesn't scale if we are going to use more than 1Tb future. > > > > > Extending RamSizeOver4G value via additional CMOS port wasn't > > > > > welcomed > > > > > either, see > > > > > http://www.seabios.org/pipermail/seabios/2010-September/000911.html > > > > > > > > > > It looks like fw_cfg interface is preferred one and > > > > > "etc/pcimem64-start" > > > > > approach doesn't have backward/forward compatibility issues. > > > > > > > > Hmm but you aren't passing in memory size - pcimem64-start > > > > merely tells bios where to put PCI devices. > > > > So how would it help? > > > If a lot of memory is reserved for memory hotplug (terabytes), that could > > > put window behind what RamSizeOver4G could address it. > > > > All we care about for a compatible bios is that it > > keep working in old hardware configurations. > > IMO there's no real need for old BIOS to work > > with e.g. memory hotplug - it's reasonable > > to ask users to update fitmware if they want > > to use this feature. > Fine with me if we don't care about strange hangs if something misused. > > But RamSizeOver4G still doesn't allow correctly place PCI window if large > amount of memory present/reserved. BTW: I don't think it's good practice to change semantics of an old interface in general. It's less confusing to leave old interface as is (obsoleting it eventually) and use a new one. > > > > > > > > > > > > > > > > > > > > > --- > > > > > > > src/fw/pciinit.c | 13 ++++++++++++- > > > > > > > 1 file changed, 12 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c > > > > > > > index b29db99..798309b 100644 > > > > > > > --- a/src/fw/pciinit.c > > > > > > > +++ b/src/fw/pciinit.c > > > > > > > @@ -18,6 +18,8 @@ > > > > > > > #include "paravirt.h" // RamSize > > > > > > > #include "string.h" // memset > > > > > > > #include "util.h" // pci_setup > > > > > > > +#include "byteorder.h" // le64_to_cpu > > > > > > > +#include "romfile.h" // romfile_loadint > > > > > > > > > > > > > > #define PCI_DEVICE_MEM_MIN 0x1000 > > > > > > > #define PCI_BRIDGE_IO_MIN 0x1000 > > > > > > > @@ -764,6 +766,15 @@ static void pci_bios_map_devices(struct > > > > > > > pci_bus *busses) > > > > > > > { > > > > > > > if (pci_bios_init_root_regions(busses)) { > > > > > > > struct pci_region r64_mem, r64_pref; > > > > > > > + u64 ram64_end = 0x100000000ULL + RamSizeOver4G; > > > > > > > + u64 base64 = > > > > > > > le64_to_cpu(romfile_loadint("etc/pcimem64-start", > > > > > > > + ram64_end)); > > > > > > > + if (base64 < ram64_end) { > > > > > > > + dprintf(1, "ignorig etc/pcimem64-start [0x%llx] > > > > > > > below present RAM, " > > > > > > > + "placing 64-bit PCI window behind RAM > > > > > > > end: %llx", > > > > > > > + base64, ram64_end); > > > > > > > + base64 = ram64_end; > > > > > > > + } > > > > > > > r64_mem.list.first = NULL; > > > > > > > r64_pref.list.first = NULL; > > > > > > > > > > > > > > pci_region_migrate_64bit_entries(&busses[0].r[PCI_REGION_TYPE_MEM], > > > > > > > @@ -779,7 +790,7 @@ static void pci_bios_map_devices(struct > > > > > > > pci_bus *busses) > > > > > > > u64 align_mem = pci_region_align(&r64_mem); > > > > > > > u64 align_pref = pci_region_align(&r64_pref); > > > > > > > > > > > > > > - r64_mem.base = ALIGN(0x100000000LL + RamSizeOver4G, > > > > > > > align_mem); > > > > > > > + r64_mem.base = ALIGN(base64, align_mem); > > > > > > > r64_pref.base = ALIGN(r64_mem.base + sum_mem, > > > > > > > align_pref); > > > > > > > pcimem64_start = r64_mem.base; > > > > > > > pcimem64_end = r64_pref.base + sum_pref; > > > > > > > -- > > > > > > > 1.8.3.1 > > > > > > > > > > > > > > > > > > > > > -- > > > > > Regards, > > > > > Igor > > > > > > > > > -- > > > Regards, > > > Igor > > > -- > Regards, > Igor > > _______________________________________________ > SeaBIOS mailing list > SeaBIOS@seabios.org > http://www.seabios.org/mailman/listinfo/seabios -- Regards, Igor _______________________________________________ SeaBIOS mailing list SeaBIOS@seabios.org http://www.seabios.org/mailman/listinfo/seabios
