--KR/qxknboQ7+Tpez
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Hi all,
1st Question :
i'm working at a bios flash utility for some pc manufacture and have trouble
in using the mmap function :(
I need access to the address space starting at 0xFFFE0000 to 0xFFFFFFFF whe=
re the flash chip copy its contents. I use the /dev/mem device driver to ac=
cess the memory environment throw the mmap function but it does not work. S=
o i decrease the size from 0x20000 to 0x20000 - getpagesize() and what happ=
ens, yes mmap exit without any error.
Why can i not mmap from 0xFFFE0000 with the size of 0x20000 bytes ?!
More background information. I have to program the vendor specific PCI devi=
ces
before i get the access to the flash contents. This PCI device handels the
write/read operations to that flash chip and the region where its contents
will be mirrored. I can NOT change the region where it will be :(
2nd Question :
Perhapps it will be a stuppid question but how can i access the mapped memo=
ry ?!
Can i use simple cpu memory access or is it required to use the read/write
function with the previous get file handle by open("/dev/mem", ..) ?!
3rd Question :
The access to the flash chip is VERY time critical. I need a function that
allows me to protect the current task from others. While accessing the flas=
h memory mapped before, NO other task should/must get processor time. Which=
technique solve this problem ?!
4th Question :
Because the pentium processors have caches it is required to disable them
before access the flash memory (you know, time critical access). So i inclu=
de
some assembler code that use the %cr0 pentium processor register but i get
segfaults while executing this source line :( How can i disable the cpu cac=
he
withou using the assembler code within the user application ?! Of course, o=
nly
root can do that.
I hope this questions fits in the mailling list because it is the last chan=
se
for me, no one else could help me...
I realy HOPE get hopeful answers, thx.
--=20
Raphal Bossek <raphael.bossek@solutions4linux.de>
PGP fingerprint: DF 6F 2C 76 46 1E B4 1C 5B A5 2E 1B FC E0 D3 F6
PGP public key: http://www.solutions4linux.de/gnusc/pgpkey.asc
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