Messages in this thread Patch in this message |  | | Date | Sat, 22 Mar 2008 11:59:48 -0700 | From | Ravikiran G Thirumalai <> | Subject | Re: [patch 4/4] x86: apic_is_clustered_box to indicate unsynched TSC's on multiboard vSMP systems |
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On Fri, Mar 21, 2008 at 07:58:21PM +0100, Ingo Molnar wrote: > >* Ravikiran G Thirumalai <kiran@scalex86.org> wrote: > >> As for the observation about probing the pci space early during the >> bootup, we call vsmp_init() much earlier during the bootup, which >> calls is_vsmp_box(), does the pci probing and caches the result in the >> flag, as you suggest. So the call in the above diff context does not >> access the pci config space as is. > >ah, i see - indeed - the trick with -1 :-) > >my point remains though: if you initialize VSMP in a separate function >anyway then please move this PCI config space access from is_vsmp_box() >into vsmp_init() and keep a pure flag return is_vsmp_box(). That way >there can be no question at all whether there are (or can be) any >side-effects of that function. >
OK. Something like this?
vSMP detection: Access pci config space early in boot to detect if the system is a vSMPowered box, and cache the result in a flag, so that is_vsmp_box() retrieves the value of the flag always.
Signed-off-by; Ravikiran Thirumalai <kiran@scalex86.org>
Index: linux.git.trees/arch/x86/kernel/vsmp_64.c =================================================================== --- linux.git.trees.orig/arch/x86/kernel/vsmp_64.c 2008-03-21 13:15:17.000000000 -0700 +++ linux.git.trees/arch/x86/kernel/vsmp_64.c 2008-03-22 11:58:42.313580356 -0700 @@ -108,25 +108,34 @@ static void __init set_vsmp_pv_ops(void) #endif #ifdef CONFIG_PCI -static int vsmp = -1; +static int is_vsmp = -1; -int is_vsmp_box(void) +static void __init detect_vsmp_box(void) { - if (vsmp != -1) - return vsmp; + is_vsmp = 0; - vsmp = 0; if (!early_pci_allowed()) - return vsmp; + return; - /* Check if we are running on a ScaleMP vSMP box */ + /* Check if we are running on a ScaleMP vSMPowered box */ if (read_pci_config(0, 0x1f, 0, PCI_VENDOR_ID) == (PCI_VENDOR_ID_SCALEMP | (PCI_DEVICE_ID_SCALEMP_VSMP_CTL << 16))) - vsmp = 1; + is_vsmp = 1; +} - return vsmp; +int is_vsmp_box(void) +{ + if (is_vsmp != -1) + return is_vsmp; + else { + printk("ScaleMP vSMPowered system detection called too early!\n"); + return 0; + } } #else +static int __init detect_vsmp_box(void) +{ +} int is_vsmp_box(void) { return 0; @@ -135,6 +144,7 @@ int is_vsmp_box(void) void __init vsmp_init(void) { + detect_vsmp_box(); if (!is_vsmp_box()) return;
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