Earlier this year, there was a discussion on linux-kernel about porting
Linux to machines originally designed for Windows CE. Among the platforms
discussed then were machines based on the Hitachi SH-3 CPUs (e.g. the
HP360LX, which uses the SH7707).
Hitachi themselves claim on various Web pages that Linux runs on the
SH-3 [1], but I've been unsuccessful so far in getting any information
about the existance of such a project, let alone its status. So this may
just be incorrect information that entered their PR system somehow and
then was propagated all over the place.
Q1: Am I on the wrong track here and is there already a place where
Linux is happily running on a SH-3 ? Or is anybody currently working
on a port ?
If the answer is "no", I might be foolish enough to try my luck myself.
Fortunately, gcc seems to support the SuperH family [2]. That's a start
at least. Also, fortunately, there's very good documentation on the
SH7707 [3,4].
Q2: Are there any known serious problems with gcc's/egcs's support for
the SH-3 ?
The next step is to boot anything with the potential of controlling the
entire hardware on that CE box. That should be pretty straightforward
when taking the LOADLIN idea: write a CE program that loads the kernel
(or a fragment of it, or a second-stage loader) from PCMCIA, RS-232,
etc., enters privileged mode, and then runs it. From there on, that
piece of code could determine its physical location from the TLB, then
run itself in physical memory (Area P1), and gradually take over the
machine.
Assuming I want to do this (e.g. if the answer to Q1 is "no"), I still
have one little problem: I don't have any machines running Windows nor
do I intend to acquire any in the forseeable future, so the "standard"
development tools for CE are unavailable. However, given that the first
stage loader has a fairly simple task (much easier than LOADLIN's), I'm
fairly sure that I'll be able to find some generous CE programmer who
can write such a thing for me.
The next two questions are fairly specific to CE and should be asked in
comp.os.ms-windows.ce, but I'll mention them here anyway for
completeness:
Q3: Does Windows CE allow any user-provided piece of software (e.g. a
driver) to gain privileged mode ? If not, I'd have to burn ROMs,
which puts the project slightly beyond my pain threshold ...
Q4: Also, is Windows CE (as on the HP360LX) able with on-board means
(e.g. after we've wiped clean all the RAM) to access a PCMCIA
Flash card or to download files from a Linux PC (e.g. using
Kermit, Zmodem, PPP, ...) over RS-232, and to run or install (if
it's a driver) them ? This question may sound trivial, but I
haven't bought the machine yet, and I don't know any HP360LX owners
in the local area either.
Many of the questions I brought up here are fairly off-topic and I'm
not very good at keeping up with linux-kernel anyway, so please send
replies to me directly. I'll post a summary to the list.
Thanks,
- Werner
[1] http://semiconductor.hitachi.com/windowsce/index.cfm?menuselection=faqs
[2] http://www.gnu.org/software/gcc/gcc.html#TOCportandopt
[3] http://semiconductor.hitachi.com/products/
h_micon/1_sh/3_sh3/H13TH007D2/pdf/h1307.pdf
[4] http://semiconductor.hitachi.com/products/
h_micon/1_sh/3_sh3/H13TP001D2/pdf/h1301.pdf
-- _________________________________________________________________________ / Werner Almesberger, DI-ICA,EPFL,CH werner.almesberger@lrc.di.epfl.ch / /_IN_R_131__Tel_+41_21_693_6621__Fax_+41_21_693_6610_____________________/- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/