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Provide less laborius way to enable busdma DMAR to only short list of devices.

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Kernel environment variable hw.busdma.default can take values 'bounce'
and 'dmar' and selects corresponding busdma backend as default.
Per-device environment variable hw.busdma.pci<domain>.<bus>.<slot>.<func>
takes the same values and overrides hw.busdma.default for the given device.

Note that even with hw.busdma.default=bounce, DMA translation engines
are still started if DMARs are enabled, to disable them use
hw.dmar.dma tunable, as before.

Sponsored by:	The FreeBSD Foundation
MFC after: 1 week
This commit is contained in:
Konstantin Belousov 2017-03-26 00:40:35 +00:00
parent e9804ab2bd
commit 70fd237c5d
1 changed files with 23 additions and 3 deletions
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26
sys/x86/iommu/busdma_dmar.c
View File

@ -74,14 +74,34 @@ static bool
dmar_bus_dma_is_dev_disabled(int domain, int bus, int slot, int func)
{
char str[128], *env;
int default_bounce;
bool ret;
static const char bounce_str[] = "bounce";
static const char dmar_str[] = "dmar";
snprintf(str, sizeof(str), "hw.busdma.pci%d.%d.%d.%d.bounce",
default_bounce = 0;
env = kern_getenv("hw.busdma.default");
if (env != NULL) {
if (strcmp(env, bounce_str) == 0)
default_bounce = 1;
else if (strcmp(env, dmar_str) == 0)
default_bounce = 0;
freeenv(env);
}
snprintf(str, sizeof(str), "hw.busdma.pci%d.%d.%d.%d",
domain, bus, slot, func);
env = kern_getenv(str);
if (env == NULL)
return (false);
return (default_bounce != 0);
if (strcmp(env, bounce_str) == 0)
ret = true;
else if (strcmp(env, dmar_str) == 0)
ret = false;
else
ret = default_bounce != 0;
freeenv(env);
return (true);
return (ret);
}
/*