[Barrelfish-users] How to use fopen on a span-ed dispatcher on Barrelfish

[Chothia Zaheer]

[+barrelfish-users]

Hi Guo,

I can reproduce the issue you describe although I don't understand the
underlying problem.  Adding the list in case someone else can comment.

The step which fails is opening a file on the remote core.  Full error message:
  ERROR: autorun1.1 in resolve_path() ../lib/vfs/vfs_ramfs.c:81
  ERROR: transport error in lookup
  Failure: (         kernel) Capability not found (empty slot encountered) [SYS_ERR_CAP_NOT_FOUND]

I also tried opening on the main thread, then reading from the remote core
which also fails:
  ERROR: autorun1.1 in read_bulk() ../lib/vfs/vfs_ramfs.c:342
  ERROR: transport error in read
  nRRFaORi:l uraeut:o r( u n 1. 1    i n  vkfersnfed_lr) eSald(o)t  s.p./elciifbi/evfds f/ovrfs _LfRPdC. c:d1oe0s0 
   oEt RcROoRn:ta ienrr oanr  einn dvpofisn_rte caadp
   [SYS_ERR_LRPC_NOT_ENDPOINT]
  Failure: (         kernel) Slot specified for LRPC does not contain an endpoint cap [SYS_ERR_LRPC_NOT_ENDPOINT]

As a workaround you may be able to register a stub which shuttles requests to
and back from core 0 for processing (using newlib_register_fsops__).

Best,

--Zaheer

From: 郭明宇 [mailto:369389319 at qq.com] 
Sent: 25 April 2013 07:11
To: Chothia Zaheer
Subject: How to use fopen on a span-ed dispatcher on Barrelfish

Hi, Zaheer:

May I ask you question about fs on Barrelfish?

I know how to read or write a file on Barrelfish. I can use:
main(){
    vfs_init();
    fopen();
    fread();
    fclose();
}

But, when I read a file in a spaned dispatcher. I got some pagefault error. I did this:
func(){
    fopen();
    fread();
    fclose();
}
main(){
    vfs_init();
    span_a_new_dispatcher_and_create_a_thread_on_it(func);
}
It says that "transport error in lookup" in lib/vfs/vfs_ramfs.c:81

I thought that I may should use vfs_init in the new dispatcher. But after I did that, it told me that vfs_init should not be called twice.

Can you please tell me, how to read a file on a span-ed dispatcher on Barrelfish?

Really really thanks,
Guo Mingyu