我尝试使用UIO而不是直接映射/dev/mem
后,无法在Xilinx Zynq上映射物理内存。虽然计划是以普通用户身份运行应用程序,而不是root
,但仍以root
运行该应用程序。mmap在UIO设备上出现EINVAL错误
显然,第一次映射是成功的,而其余完成到相同的文件描述符12
(/dev/uio/ps2pl
)失败。虽然明显的差异是偏移量,但它在范围之内(请参阅设备树),并且页面对齐正确。此应用程序与/dev/mem
配合良好。
通过用strace
运行中观察到的错误是:
open("/dev/uio/ps2pl", O_RDWR|O_SYNC) = 12
open("/sys/bus/i2c/devices/0-0050/eeprom", O_RDONLY) = 13
fstat64(13, {st_mode=S_IFREG|0600, st_size=8192, ...}) = 0
_llseek(13, 0, [0], SEEK_SET) = 0
read(13, "\1\1\0\0\0\0\0\0", 8) = 8
read(13, "(\\\217\2(\\\217\00233333333\0\0\0\0\0\0\0\0(\\\217\2(\\\217\2"..., 4096) = 4096
close(13) = 0
mmap2(NULL, 48, PROT_READ|PROT_WRITE, MAP_SHARED, 12, 0) = 0xb6f93000
mmap2(NULL, 48, PROT_READ|PROT_WRITE, MAP_SHARED, 12, 0x400000) = -1 EINVAL (Invalid argument)
mmap2(NULL, 196608, PROT_READ|PROT_WRITE, MAP_SHARED, 12, 0x200000) = -1 EINVAL (Invalid argument)
mmap2(NULL, 196608, PROT_READ|PROT_WRITE, MAP_SHARED, 12, 0x100000) = -1 EINVAL (Invalid argument)
--- SIGSEGV {si_signo=SIGSEGV, si_code=SEGV_MAPERR, si_addr=0x1f} ---
+++ killed by SIGSEGV +++
Segmentation fault
作为装入内核的设备树:
# /root/dtc/dtc -f -I fs /sys/firmware/devicetree/base/amba_pl/ps2pl\@40000000/
ERROR (name_properties): "name" property in/is incorrect ("ps2pl" instead of base node name)
Warning: Input tree has errors, output forced
/dts-v1/;
/{
reg = <0x40000000 0x40000000>;
name = "ps2pl";
interrupts = <0x0 0x44 0x4>;
compatible = "generic-uio";
interrupt-parent = <0x3>;
};
的UIO映射的尺寸足够大,以容纳上述mmap
尺寸和补偿:
# cat /sys/devices/soc0/amba_pl/40000000.ps2pl/uio/uio0/maps/map0/size
0x40000000