4MByte limit in IMFS for each file?
joel.sherrill at OARcorp.com
Mon Feb 24 00:09:51 UTC 2003
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Angelo Fraietta wrote:
> So what is the largest file size?
From a comment imfs.h:
* The data structure for the in-memory "memfiles" is based on classic
* block_ptr is a pointer to a block of IMFS_MEMFILE_BYTES_PER_BLOCK in
* length which could be data or a table of pointers to blocks.
* Setting IMFS_MEMFILE_BYTES_PER_BLOCK to different values has a
* impact on the maximum file size supported as well as the amount of
* memory wasted due to internal file fragmentation. The following
* is a list of maximum file sizes based on various settings
* max_filesize with blocks of 16 is 1,328
* max_filesize with blocks of 32 is 18,656
* max_filesize with blocks of 64 is 279,488
* max_filesize with blocks of 128 is 4,329,344
* max_filesize with blocks of 256 is 68,173,568
* max_filesize with blocks of 512 is 1,082,195,456
> till wrote:
>> I hit the same limit when copying large files from TFTPFS to IMFS for
>> loading them with CEXP.
>> You have to increase the IMFS blocksize (the default being 128b -
>> AFAIK, the max number of blocks is limited, hence increasing the
>> blocksize will help) in the file
>> look for IMFS_MEMFILE_BYTES_PER_BLOCK
>> -- Till
>> Thomas Doerfler wrote:
>>> it's me again :-)
>>> When I tried out my "fileio" sample, I hit a strange 4MByte limit
>>> when creating files in the IMFS. I was working on a PC386 target
>>> with 16MByte of memory (and most of it was always available on the
>>> When I tried to create big files (like 8MB), the write call always
>>> failed (with a "no space left on device" error), directly after
>>> reaching a 4MByte file size boundary.
>>> This limit does not exist on the DOSFS, only when writing to the
>>> IMFS. I tried it out on a MBX8xx system (with 16MByte of RAM) and
>>> there I hit the limit also after 4MBytes.
>>> I was browsing through the IMFS sources and did not find any reason
>>> for this limitation, and I did not yet run the test with a debugger.
>>> Any hints on that issue?
>>> IMD Ingenieurbuero fuer Microcomputertechnik
>>> Thomas Doerfler Herbststrasse 8
>>> D-82178 Puchheim Germany
>>> email: Thomas.Doerfler at imd-systems.de
>>> PGP public key available at: http://www.imd-
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