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s390/pci: add parameter to disable usage of MIO instructions

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Allow users to disable usage of MIO instructions by specifying pci=nomio
at the kernel command line.

Signed-off-by: Sebastian Ott <sebott@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Sebastian Ott 2019-04-18 21:39:06 +02:00 committed by Martin Schwidefsky
parent 71ba41c9b1
commit 5627130380
2 changed files with 7 additions and 1 deletions
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1
Documentation/admin-guide/kernel-parameters.txt
View File

@ -3395,6 +3395,7 @@
this removes isolation between devices and
may put more devices in an IOMMU group.
force_floating [S390] Force usage of floating interrupts.
nomio [S390] Do not use MIO instructions.
pcie_aspm= [PCIE] Forcibly enable or disable PCIe Active State Power
Management.

7
arch/s390/pci/pci.c
View File

@ -850,6 +850,7 @@ static void zpci_mem_exit(void)
}
static unsigned int s390_pci_probe __initdata = 1;
static unsigned int s390_pci_no_mio __initdata;
unsigned int s390_pci_force_floating __initdata;
static unsigned int s390_pci_initialized;
@ -859,6 +860,10 @@ char * __init pcibios_setup(char *str)
s390_pci_probe = 0;
return NULL;
}
if (!strcmp(str, "nomio")) {
s390_pci_no_mio = 1;
return NULL;
}
if (!strcmp(str, "force_floating")) {
s390_pci_force_floating = 1;
return NULL;
@ -881,7 +886,7 @@ static int __init pci_base_init(void)
if (!test_facility(69) || !test_facility(71))
return 0;
if (test_facility(153))
if (test_facility(153) && !s390_pci_no_mio)
static_branch_enable(&have_mio);
rc = zpci_debug_init();