Re: My Summer of Code Project
Alex Roman [EMAIL PROTECTED] writes: Hi Alex, My name is Alex Roman and I have been selected as a Summer of Code student for the GRUB2 project. I thought I'd introduce myself and my project. I am a second year student at the University of Waterloo (just finished 2A, first term of second year). I have experience developing in low-level environments in C and assembly. Welcome! If you have any questions, don't be afraid to ask on the list and I won't mind if you ask me things about GRUB 2, etc. off-list. There is also a GRUB 2 IRC channel (#grub on irc.freenode.net) where GRUB 2 developers waste some of their time :-). Now about my project. I will be adding CD-ROM booting functionality to GRUB2. The first stage of the project will attempt to use BIOS calls to achieve this functionality (which is, of course, dependent on the BIOS's capabilities, standards compliance, etc.). The second stage will involve writing a complete ATA/ATAPI driver which would bypass the BIOS completely, thus allowing it to work on virtually any system out there. That sounds great! Unfortunately I only have access to ATAPI CD-ROM drives, so I won't be able to work on SCSI and/or USB, however I will try to separate the system to load the boot image from the driver itself as much as possible so that future driver developments for SCSI and USB will just be sort of drop-in replacements. There is an iso9660 fs implementation already, so you only need to provide a block driver. After that it is easy to test if it works. If you want to know how to write a block driver for GRUB, have a look at loopback.c. Or have a look at the block driver for open firmware. Both are quite easy to understand. But don't be afraid to ask questions about the design of GRUB 2. So, just thought I'd talk a bit about what I'll be doing... Please keep talking :-). Really, it is a waste of time if you are heading in the wrong direction. Share your ideas, send patches to the list if you want us to review your code, etc. Feedback is one of the things that makes it great to work on Free Software projects. You communicate with lots of people, you learn new stuff, it improves the quality of your code, etc. Don't be afraid to look stupid by asking stupid questions or by sending in patches which don't look really nice. Thank you for your attention and time. I'm sure I'll have lots of questions in the months to come. :) :-) -- Marco ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
Alex Roman [EMAIL PROTECTED] writes: Hi Alex, Please don't top quote, it is confusing ;-). Interesting piece of code... Yet another example of showing how to implement an ATA/IDE controller driver :) Yeah. btw, do you know http://www.osdever.net? If you are looking for even more information, I could have a look at which books about this subject I can recommend. Right now I'm pondering whether it is worth implementing a BIOS calls CDROM boot support, or whether I should just go right ahead and do it all with the ATA controller. Both are important! Really... You should know GRUB 2 is designed to be portable and runs on lots of different systems. When the firmware gives access to the CDROM drive, this is usually a nice feature to have. One thing is that you have support for it, even if it is SCSI (which you won't implement) or something else which is terribly obscure :-). Another nice reason you want this is that usually the firmware tells you which drive you booted from. For example, when you boot from a CDROM drive it is easy to figure out which drive to load all files from. Think of livecds, etc. Actually, an IDE driver is a terrible thing to have. But it is required for broken systems like the PC. Some BIOSes do not have CDROM support. Other don't give you access to the CDROM drive when you do not use it for booting. I'm not sure how IDE controllers work on PPC, since I've unfortunately never used the architecture... If you make sure you keep endianess in mind, you usually will be doing the right thing. Besides that, on the PPC all IO is memory mapped. You can have a look at linux to see how it deals with IO access. Technically, if the ATA/IDE driver is there, implementing the ATAPI command set to talk to the CDROM and interpreting the El-Torito spec shouldn't be that hard. Yeah :) If CD-ROM drives are ATAPI on all platforms (where they use ATA), and the ATA code is there, the ATAPI and El Torito layer should stay cross-platform. The interesting bit will be making it so that plugging in a SCSI driver will require the least amount of code change. El Torito is PC only, no? Anyways, I'm kind of rambling for now... Until the official code start day I'll do some more reading and investigating how it would be best to tie the code into GRUB2 to give the most elegant solution. One good way to start is by just fixing random things in GRUB 2. Play with grub-emu, make a floppy image with GRUB 2 on it and boot it from qemu. Setup a good development environment (talking about this is perhaps a smart thing to do, if you lack the experience). For some other summer of code projects (like ffmpeg), the students we required to send in patched before they were qualified. IOW: you couldn't be accepted, unless you sent in patches that were good enough to make it into SVN. By doing this they showed they are capable enough to work on the project. But besides that, and that is what I am trying to say, is that it usually helps if you poke around a bit and play with the code, you don't even have to do something useful. And ask lots and lots of questions :-) -- Marco ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
Alex Roman [EMAIL PROTECTED] writes: Hi, On 25/04/07, Marco Gerards [EMAIL PROTECTED] wrote: Alex Roman [EMAIL PROTECTED] writes: Hi Alex, Please don't top quote, it is confusing ;-). GMail is doing it... Sorry :( np, you seem to have fixed it :-) [...] If you are looking for even more information, I could have a look at which books about this subject I can recommend. IIRC someone was saying that GSoC students will get an O'Reilly Safari books account. If that's so, hopefully books there will be useful. Perhaps the O'Reilly books about the Linux kernel internals. Other than that, I doubt that there are many interesting books... But who knows. :-) [...] I'm not sure how IDE controllers work on PPC, since I've unfortunately never used the architecture... If you make sure you keep endianess in mind, you usually will be doing the right thing. Besides that, on the PPC all IO is memory mapped. You can have a look at linux to see how it deals with IO access. I might need a bit of help as to how I should keep the endianness at bay... Are there macros or functions currently in GRUB2 that are architecture dependent and convert a number to the right endianness? Are there other mechanisms? Yeah, for example grub_be_to_cpu32 to convert a 32 bits BE integer to the host format. You can find all macros in include/grub/types.h. Technically, if the ATA/IDE driver is there, implementing the ATAPI command set to talk to the CDROM and interpreting the El-Torito spec shouldn't be that hard. Yeah :) If CD-ROM drives are ATAPI on all platforms (where they use ATA), and the ATA code is there, the ATAPI and El Torito layer should stay cross-platform. The interesting bit will be making it so that plugging in a SCSI driver will require the least amount of code change. El Torito is PC only, no? From what I've read, it seems like El Torito is just a standard for the layout of the ISO, it shows how the boot image is stored in the iso9660 image. Wikipedia knows all :P http://en.wikipedia.org/wiki/El_Torito_(CD-ROM_standard) Right, but it is only used on the PC AFAIK. For example, Open Firmware (the BIOS on the PPC Macs) have ISO 9660 support and can read kernels and bootloaders directly from the filesystem. Anyways, I'm kind of rambling for now... Until the official code start day I'll do some more reading and investigating how it would be best to tie the code into GRUB2 to give the most elegant solution. One good way to start is by just fixing random things in GRUB 2. Play with grub-emu, make a floppy image with GRUB 2 on it and boot it from qemu. Setup a good development environment (talking about this is perhaps a smart thing to do, if you lack the experience). Yes, I need to do that. Setting one up shouldn't be a problem. I've built GRUB1 before on linux... And besides vim (don't want flame wars, to each their own!), GNU devel tools (gcc, make, binutils, etc) and a shell, what else do I need? :-) For GRUB 2 you will need to install ruby as well. What I actually meant with a good development environment is setting up qemu or so. Or when you want to test things on real hardware you can better use networking instead of messing around with floppies. Doing things right from the start can save you time :-). For some other summer of code projects (like ffmpeg), the students we required to send in patched before they were qualified. IOW: you couldn't be accepted, unless you sent in patches that were good enough to make it into SVN. By doing this they showed they are capable enough to work on the project. But besides that, and that is what I am trying to say, is that it usually helps if you poke around a bit and play with the code, you don't even have to do something useful. And ask lots and lots of questions :-) I should perhaps add some debugging messages to see how code is executed, the general flow of the bootloader... Have a look at grub_dprintf. It prints debug messages depending on a variable. For example, use set debug=all on the GRUB prompt. I think it is easier for you to start playing with grub-emu to understand how things in general work. Although it will be useless to you when you start working on your project. -- Marco ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
On Wednesday 25 April 2007 06:49, Alex Roman wrote: Right now I'm pondering whether it is worth implementing a BIOS calls CDROM boot support, or whether I should just go right ahead and do it all with the ATA controller. It is definitely worth doing. When BIOS works gracefully, you do not have to worry about interference with BIOS functions, and it will work, regardless of the type of a drive (e.g. SCSI or USB). And, if my understanding is correct, recent BIOSes are not that buggy with this regard, so it is the best solution in a long term. Also this is the easiest thing to implement. Thus I specified this as the first task to do. Besides that, device drivers would be useful even for some other architectures, potentially. So I would say that both are equally important for GRUB. But our priority is to motivate GRUB Legacy users to switch to GRUB 2, so supporting PC BIOS is more urgent, IMO. Technically, if the ATA/IDE driver is there, implementing the ATAPI command set to talk to the CDROM and interpreting the El-Torito spec shouldn't be that hard. If CD-ROM drives are ATAPI on all platforms (where they use ATA), and the ATA code is there, the ATAPI and El Torito layer should stay cross-platform. Potentially, yes. But I am not sure if it is feasible, because PC has more restriction. Because a drive must be accessible via BIOS calls, the code must be small enough to fit into somewhere below 1MB. In addition, such code needs to be, at least partially, 16-bit code for BIOS calls. But I am afraid that 16-bit code support by GCC is quite poor, so you would have to implement the code in assembly, thus it would result in non-portable code. Okuji ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
On Monday 23 April 2007 02:01, adrian15 wrote: Hello list, My name is Alex Roman and I have been selected as a Summer of Code student for the GRUB2 project. I will be adding CD-ROM booting functionality to GRUB2. Welcome! Cdrom booting funcionality for grub2 is a good piece of news. The first stage of the project will attempt to use BIOS calls to achieve this functionality (which is, of course, dependent on the BIOS's capabilities, standards compliance, etc.). Ok. That's how it works in Grub legacy I suppose. Nope. This is a different thing. This is a new feature which is not present in GRUB Legacy. Although people often mistake this, booting a CD from GRUB is quite different from booting a GRUB installed into a CD. GRUB Legacy has the latter feature, but not the former one. GRUB 2 needs to support both cases, but I prefer to see something not present in GRUB Legacy implemented in GRUB 2 first. Okuji ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
On Wednesday 25 April 2007 18:41, Alex Roman wrote: For GRUB 2 you will need to install ruby as well. What I actually meant with a good development environment is setting up qemu or so. Or when you want to test things on real hardware you can better use networking instead of messing around with floppies. Doing things right from the start can save you time :-). How can I tell qemu to boot grub? last I checked qemu took a hard drive image that it booted from. I have documented a howto on the wiki: http://grub.enbug.org/TestingOnX86 Although the page says bochs, you can do the same with qemu. When testing, I myself often use qemu with a floppy image. This is quite easy. I also use a hard disk image from time to time, but it is a bit more painful to set up a correct image than a floppy image. For real systems, I usually use PXE or a USB key. Have a look at grub_dprintf. It prints debug messages depending on a variable. For example, use set debug=all on the GRUB prompt. I think it is easier for you to start playing with grub-emu to understand how things in general work. Although it will be useless to you when you start working on your project. What is grub-emu? Look at the directory util. In the current version, it is built only if you specify --enable-grub-emu to configure. Okuji ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 You should probably have a look at http://www.linuxbios.org/FILO maybe you can salvage something. FILO supports booting from ElTorito bootable CD media, uses 32-bit mode, and it is free of bios calls. Unfortunately its x86 only, although some work has been done to get it running on PPC. regards DevH Alex Roman wrote: Hello list, My name is Alex Roman and I have been selected as a Summer of Code student for the GRUB2 project. I thought I'd introduce myself and my project. I am a second year student at the University of Waterloo (just finished 2A, first term of second year). I have experience developing in low-level environments in C and assembly. Now about my project. I will be adding CD-ROM booting functionality to GRUB2. The first stage of the project will attempt to use BIOS calls to achieve this functionality (which is, of course, dependent on the BIOS's capabilities, standards compliance, etc.). The second stage will involve writing a complete ATA/ATAPI driver which would bypass the BIOS completely, thus allowing it to work on virtually any system out there. Unfortunately I only have access to ATAPI CD-ROM drives, so I won't be able to work on SCSI and/or USB, however I will try to separate the system to load the boot image from the driver itself as much as possible so that future driver developments for SCSI and USB will just be sort of drop-in replacements. So, just thought I'd talk a bit about what I'll be doing... Thank you for your attention and time. I'm sure I'll have lots of questions in the months to come. :) -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGLmM6CbmO6P7mspMRCkGqAJ9I6u7BlaiHWjJ1T5qBrwuQ3wyy0QCbBE+Q QsyJ7MVm3zNEfmA8LuVqcGE= =L3H4 -END PGP SIGNATURE- ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
* Devils-Hawk [EMAIL PROTECTED] [070424 22:06]: You should probably have a look at http://www.linuxbios.org/FILO maybe you can salvage something. FILO supports booting from ElTorito bootable CD media, uses 32-bit mode, and it is free of bios calls. Unfortunately its x86 only, although some work has been done to get it running on PPC. FILO has been used on PPC for quite some time. For simplicity, that version has been integrated into LinuxBIOS directly though. There is a GSoC project for porting Grub2 to work in LinuxBIOS. It will be realized by Patrick Georgi [EMAIL PROTECTED]. Maybe you guys can join efforts on solving this issue? I would like to see FILO die. Which will happen once GRUB2 will work on an x86 machine without 16bit real mode legacy BIOS. Stefan -- coresystems GmbH • Brahmsstr. 16 • D-79104 Freiburg i. Br. Tel.: +49 761 7668825 • Fax: +49 761 7664613 Email: [EMAIL PROTECTED] • http://www.coresystems.de/ ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
Interesting piece of code... Yet another example of showing how to implement an ATA/IDE controller driver :) Right now I'm pondering whether it is worth implementing a BIOS calls CDROM boot support, or whether I should just go right ahead and do it all with the ATA controller. I'm not sure how IDE controllers work on PPC, since I've unfortunately never used the architecture... Technically, if the ATA/IDE driver is there, implementing the ATAPI command set to talk to the CDROM and interpreting the El-Torito spec shouldn't be that hard. If CD-ROM drives are ATAPI on all platforms (where they use ATA), and the ATA code is there, the ATAPI and El Torito layer should stay cross-platform. The interesting bit will be making it so that plugging in a SCSI driver will require the least amount of code change. Anyways, I'm kind of rambling for now... Until the official code start day I'll do some more reading and investigating how it would be best to tie the code into GRUB2 to give the most elegant solution. Cheers, Alex On 24/04/07, Devils-Hawk [EMAIL PROTECTED] wrote: -BEGIN PGP SIGNED MESSAGE- Hash: SHA512 You should probably have a look at http://www.linuxbios.org/FILO maybe you can salvage something. FILO supports booting from ElTorito bootable CD media, uses 32-bit mode, and it is free of bios calls. Unfortunately its x86 only, although some work has been done to get it running on PPC. regards DevH Alex Roman wrote: Hello list, My name is Alex Roman and I have been selected as a Summer of Code student for the GRUB2 project. I thought I'd introduce myself and my project. I am a second year student at the University of Waterloo (just finished 2A, first term of second year). I have experience developing in low-level environments in C and assembly. Now about my project. I will be adding CD-ROM booting functionality to GRUB2. The first stage of the project will attempt to use BIOS calls to achieve this functionality (which is, of course, dependent on the BIOS's capabilities, standards compliance, etc.). The second stage will involve writing a complete ATA/ATAPI driver which would bypass the BIOS completely, thus allowing it to work on virtually any system out there. Unfortunately I only have access to ATAPI CD-ROM drives, so I won't be able to work on SCSI and/or USB, however I will try to separate the system to load the boot image from the driver itself as much as possible so that future driver developments for SCSI and USB will just be sort of drop-in replacements. So, just thought I'd talk a bit about what I'll be doing... Thank you for your attention and time. I'm sure I'll have lots of questions in the months to come. :) -BEGIN PGP SIGNATURE- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQFGLmM6CbmO6P7mspMRCkGqAJ9I6u7BlaiHWjJ1T5qBrwuQ3wyy0QCbBE+Q QsyJ7MVm3zNEfmA8LuVqcGE= =L3H4 -END PGP SIGNATURE- ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel -- Alex Roman [EMAIL PROTECTED] ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
Re: My Summer of Code Project
Hello list, My name is Alex Roman and I have been selected as a Summer of Code student for the GRUB2 project. I will be adding CD-ROM booting functionality to GRUB2. Welcome! Cdrom booting funcionality for grub2 is a good piece of news. The first stage of the project will attempt to use BIOS calls to achieve this functionality (which is, of course, dependent on the BIOS's capabilities, standards compliance, etc.). Ok. That's how it works in Grub legacy I suppose. The second stage will involve writing a complete ATA/ATAPI driver which would bypass the BIOS completely, thus allowing it to work on virtually any system out there. I suppose that it is going to be difficult. I give you my encouragement! Unfortunately I only have access to ATAPI CD-ROM drives, so I won't be able to work on SCSI and/or USB, I don't have either. however I will try to separate the system to load the boot image from the driver itself as much as possible so that future driver developments for SCSI and USB will just be sort of drop-in replacements. So, just thought I'd talk a bit about what I'll be doing... Comunication is a good thing. Thank you for your attention and time. I'm sure I'll have lots of questions in the months to come. :) If this happens, it's a good sign of grub2 development health. adrian15 ___ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
